Everyone thinks the SBF or SBC/BBC are obsolete unless you spend time on various racing forums. I dont mind seeing an LS9 in a Mustang, but if I see one more 5.3l swap, Im going to puke, lol.
The 8.2" deck SBF is an awful practical engine for a swap into a car with limited space. A 331 SBF with High Port heads will easily hit 500hp and isnt particularly expensive. They sound wonderful shifting at 8000rpm.
The LS is a great motor and is very cost effective. I am often baffled when I see a $100k+ car build and then they dump a crate LS3 into it. As an example they have come out with an updated W409 motor bored to 509ci. The engine puts out near 700hp, is available in all aluminum with efi. Butler Performance is doing similar with Pontiac motors. Another vendor is coming out with new Oldsmobile stuff.
A few years ago, the Gen 4 motor made every Gen 3 obsolete. In the near future the Gen 5 may do the same. Using the cars original engine architecture with new high performance blocks, heads and efi make for a more timeless car build, It also honors the heritage and DNA of the car. For the record, I am not a numbers matching guy.
I am working on a C2 Corvette with a 700hp+ SBC with 8 stack efi and have a chrome bumper C3. The C3 will get a 900hp+ BBC. I stuck with traditional modernized engines for the reasons stated above. Both engines are/will be NA, built with off the shelf parts!
For the record that Mustang with the LS9 could have been built with a 650hp 9.5" deck SBF for a lot less money. The weight argument is moot when you factor in LS9 dry sump and supercharger weight.
You could order the drag pack motor with the 8 stack and still be $3k-$4k under the cost of the LS9 with all of the hardware. Either engine is available in aluminum.