Oh, no..........sacrilege! lol No need for that......a 351W block is few hundred bucks, and a stroker kit (another $1,500, maybe?) will give you a 400 cu. in. small block than can EASILY put out 400hp+ & 450 lbs/ft+ of torque. All that, N/A!
Not trying to put down the LS1; it's a great engine. I've just never been of a fan of those Frankenstein conversions.
OP: The idea sounds good in theory, but I'm sure there are going to be other things coming up throughout this build that aren't going to allow you break even in the end. Remember; the GT has bigger brakes, too. Not just rotors and calipers, but the brake booster and maybe the brake lines. The radiator/cooling system may change, and the a/c components and other accessories may have to be adapted to fit the V8 engine, as well. The gauge cluster is only going to read 120mph. Also, to feed that hi-po engine, you'll probably need a dual fuel pump system off of a GT500.
Want my idea? Find a late model Lincoln Mark VIII, and get the 32V 4.6L drivetrain off of one of those. If you're going to do internals anyway, might as well stroke it to get a 5.0L 4V and make something special out of that. My
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