At 500fwhp it would be cheaper to do a 383 rotating assy, port the heads/intake and buy a FAST 2.0.

At 700rwhp you need to go LS, and be prepared to spend some money. Another option for 700rwhp is a BBC.:)

While a BBC is sexy sounding I'm not sure I want the weight. If I do swap the motor I'll 100% go fuel injection too.

Basically what I have, 383 (10-8comp), Dart 210 (small port Job) Heads, Fast 2.0, about 400 rwhp (570 with a 200 shot of nos) through a automatic with a 3500 stall. Think with the right heads can get it to around 450RWHP, and still keep it road friendly. I have not had it dynoed since I installed the Fast 2.0, but it drives really nice, starts up on cold days without touching the throttle. (10.69 1/4 mile with carb no suspension tuning))

I agree a BBC would be too heavy. The real issue is which EFI system. Holley, FAST, MSD, who makes the best throttle body EFI? They all just keep getting better.

This question is in my opinion, comes down to who you ask. Reason I say that is I researched the same thing for months and had good/bad on all of them. Its really coming down to looking at what they all do, and put all the inputs together and chose your poison. I have the Fast 2.0, because I loved what I read. Its has been a small challenge so far to get it to being that "Plug and Play" as advertised, but right now its working good (didn't say great/awesome), but hopefully with more time it will be. Thats my 2 cents.

There's also the possibility of running a LSx PCM on the SBC. www.eficonnection.com has the setup.

It really can get confusing to decide which EFI system to utilize. I personally am in favor of the LSx PCM whenever possible. None of the aftermarket systems come close to having the level of investment in them that GM put into the LSx PCM. However, do you need all that the LSx PCM has to offer to achieve your goals? I've built EFI systems utilizing a L98 SD PCM. It worked great and this was just a few years ago. So, yeah, it gets confusing and difficult to decide.

What I would recommend is that you focus on achieving your power goals properly and reliably first. After all, EFI is not needed in order to achieve your power goals. Then, I would decide which EFI system to go with. Just factor the extra cost of EFI on the LSx engine into the initial cost since chances are you'll buy a pullout that has a perfectly adequate PCM already there.

Thanks for the link and the info. Just want to point out a few things with my build to help with more info.

I guess I shouldn't have really stated power as an overall goal. It'd be nice to have 700whp but I'm not 100% set on it, I'm not trying to hit a 1/4 mile goal or dyno # goal. This will be a street/road course/autocross car.

It sounds like you're suggesting that going EFI on the SBC will not take the same initial cost as going EFI on an LSx setup, why? The LSx will already have what's needed on the motor itself and the rest would be the same as going EFI on the SBC, no? Fuel lines, tank, pump, etc. Or am I missing something here? I don't want to run an external pump from the tank, so I'll be getting a new tank for that.

Now I'm actually leaning towards having someone re-tune my SBC and Carb setup and doing all my underbody first. I want bolt on subframe/suspension front and rear. Thinking of doing that first since I have an already decently solid SBC build. I think it's just not tuned correctly for it's new location (GA vs CA)

Oh and I do plan to run a GM ECU not an aftermarket/standalone unit. From the tuners I've spoken with I see no need to go aftermarket, both for N/A and boost applications.

Honestly, I forgot your initial question with my last reply. I was merely thinking power production.

You're correct about the other upgrades needed to supply an EFI engine. Those upgrades don't care what engine you're running. Fuel supply volume and pressure required dictates the fueling system mainly.

I'm actually doing my suspension and chassis changes first since I have a running engine. I figure it will be more fun to drive that way. It already moves on its own and I'm not trying to race anyone. Eventually, I'll start building the new engine after I finally decide which direction I'm going. So I certainly don't think that's an incorrect path to take.

The LSx PCMs read up to 3 bar I believe. That's 45 psi. 1 bar is approximately 15 psi. They make excellent PCMs for street boosted applications.

The 3 bar range is 0-100kpa vacuum and 100-300kpa boost, still 30psi boost is going to get the job done for most.

Really you could make 700rwhp on a basically stock LQ9 or LQ4. (just cam/springs/forced induction). If you want to be very safe about it then throw rods and pistons in any LS and it would make that power forever.

After running super reliable LS combinations for years I would personally never consider using a sbc or bbc again.

You give up some drivability with the 2.0.

I encourage you to download the software from all the different manufacturers and compare them for yourself before you buy anything.