There is no question reliable HP per Dollar the 351w is hands down the winner due to the fact that it has been in existence since the late 60`s. In 40 years the 4.6 or 5.4 will be cheap do build reliable power. You have to remember most of the performance parts are designed to be sold to racers [dirt,scca etc] Once they sell alot of cranks and rods and pistons they can make them cheaper because it becomes routine to make them. Someone mentioned shm blocks well in 10 years i would guess they would drop 50% in price.
I finnally got back to my project and I have my 383 w almost ready. A 454 is way to much for a stock block, and since you mentioned the kite factor it probably wont be worth the extra headachs for that little more power and since you dont care about 200 extra lbs build a big block. I though the windsor was alittle to cookie cutter for me so i decided to make a semi unique one 68' block has about 17 lbs more weld on the webbings so you get a true 150 hp rating over the later block. My friend is putting 1450hp through his 69 stock block in his funny car. I realize this is the exception and not the rule but the early 351 is very beefy. Then i bought a chp forged crank, rods [6 inch] and pistons. Im getting tfs wanna be heads same castings but cnc`d and 2/3rds the price 2.05/1.70 But instead of the holley 4barrel im using a trick flow efi intake, because im going to rev her to 7200 I`m getting the track heat. Also im plumbing a t-72 turbo. I love the maf injection because it really is like have a carb tuner all the time under your hood wrenching as you goose it. So i believe its not the base engine you use its the heads, fuel delivery and power adder that makes it for me. An injected/turbo 383/w is the perfect muscle/modern engine for me, it has the bark of the pushrod v8 and the whine of the turbo with the versitility of maf injection.
Chad