Grumpy you are certainly right custom building an engine can usually bring you to a much lower price for a build. But I can get 1,000hp out of a crate LSX right now for $15k. Maybe less. Out of a 6.2L. And it can hold a butter smooth idle. And it can get good gas mileage when your foots not in it. With the boost ready LSX376 and a pd blower. With all the defected lsa cores selling on ebay so cheap, I might be able to bring that figure down as low as 13k or even 12. And that is with a crate engine and not doing a damn thing to it but swapping the intake manifold and pinning the crank so the balancer doesn't slip.
Prices for LS stuff was high 10 years ago. Today it is LT that commands a premium and there is absolutely no good reason to swap anything but LS, LQ, or LSX unless you have the money for LT. I know I am gonna be vilified by a lot for these claims. It is just an observation from being so deep in building so many. It is what everybody wants. To create the same level of control system on an old sbc or bbc pushes the cost of such a build WAY over what an ls setup with harness and controller would cost. And I am not talking about that toy efi carb replacement junk, either. I mean a real controller that measures crankshaft speed in between ignition events and records the differences in camshaft and crankshaft variances from timing component slack. I am talking about linking the ignition timing to a pair of sensitive knock sensors, And timing the fuel injector pulse to the opening of each valve on a given cylinder so the fuel doesn't pool up on top of the valve and cook waiting for it to open. Sequential fuel injection. And the only way to get it is with a cam and crankshaft position sensor. There is one solution to put a cam and crank sensor on a sbc or bbc and this timing cover, sensors, cam sprocket and crank reluctor is, well, it is this:
https://www.eficonnection.com/home/...-signal-kits/efi-58x-product-line/efi-58x-bbc
And that is just to create the proper input signal for a good controller. It will take thousands of dollars to apply an LS level control solution to an older engine platform. The cost of doing these conversions is more attractive for an LS. We are coming up on the end of 2016. The LS engine family is 20 years old now.
My claim of 1,000hp for $15k is this engine:
http://www.chevrolet.com/performance/crate-engines/lsx-376-b15.html
And this blower:
http://www.vortechsuperchargers.com/page.php?id=45123
And then you would want to add an intercooler and some extra piping and a good tune and a 3 bar map sensor.