My opinion keeps getting me into virtual fist fights with the resident suspension gurus. I'm the first to admit that my viewpoint is based almost entirely on subjective experience.
I get to drive a wide range of cars back to back. Life is good. I'm lucky enough to share shop space with a variety of different pro-touring F-body cars (As well as the Fairlane built by Charlie Libby). I get to hop out of one car and into the next for direct comparison. It's all street driving, but fun and useful nonetheless. Here's a picture:
And here's the list:
-Red 69 Coupe: 21st Century C5 clip; one-off torque arm rear, 8 point roll cage, 255/335, aluminum SBC 400, 4L80E paddle shift.
-White 69 vert: Stock clip with full DSE upgrade, ATS spindles and steering box; Hotchkis leafs rear 245/255, 383/T56.
-Green 69: Pro Street. Does nice burnouts.
-Gold 68: Modded C4 tubular clip, full cage, DSE 3" leafs rear; 255/275 all iron 406/4L60E paddle shift.
-Fairlane: Channelled body over tube frame with truck arms; 315's all the way around; 392 Stroker/Richmond 6 speed.
-Blue 68: Just started this one. Will have AirRide Street Challenge kit 255/275 (40's!) Not sure about engine/trans. probably 4L80E paddle shift.
I don't care what any of the "theorists" say about geometry similarities between modded-stock and aftermarket clips. The two clip'd cars (gold and red) are
WAY easier to drive than the modded stock clip car. I can therefore drive them faster with confidence. I suspect the difference has more to do with rear-steer steering box (stock clip) VS front steer R&P (aftermarket clip) than anything else. It's important to note that the upgraded clip car (white) is a convertible. Soon I'll have an Air Ride Street Challenge coupe for comparison as well. And some day I hope to convert the gold car to an AME full frame car with 3 link.
If you're doing the welding and fab work yourself and choose quality parts, then it makes sense to extensively mod a front clip as you've described. Just be sure to use ATS spindles. If you're paying for labor, the dollars add up real quick. Even if the difference in cost is $1000, I would still go with an AME or DSE clip.