Yea, I got lucky on Ebay with mine. I got the LS1/T56 from a 99 firebird with 28,000 on it and paid a little less than 4000 with shipping. Getting a whole car is not necessary. I used aftermarket parts and Datsun parts.
Speartech made the harness.
JTR did the headers and radiator.
Fan came from a Taurus.
Ripped out most of the electrical system and re-wired it myself (that was stupid, should have gotten the painless lighting and relay kit).
John’s cars supplied the mounts, the adapters for the Datsun senders and the A/C (not yet installed).
I removed the power steering pump from the engine and re-routed the belt system. Got a cam , heads, LS6 intake, 30 lb. injectors, ported TB, and did a homemade air intake then tuned the computer using EFI live and ran magnaflow mufflers that dump just before the axle to scare away rice and act as a leaf blower for my driveway. At 900 rpm it really has a very noticeable lope to it. I cant go to the store without somebody approaching me and asking me about it. Then I get into a 20 minute conversation and sometimes forget what I went to the store for.
This week has been dedicated to getting heat. The 28-year-old Datsun heater coil, valve, and control module were toast, along with all the open cell foam they used in the unit. I rebuilt the unit and hooked it up tonight and tested it. Oh joy, heat! Tomorrow the dash goes back in and I’m on the road for the winter.
FWIW I am now in the process of fitting the LS1 with a 2003 Vette over the radiator air intake fitting and matching air filter to the Z. Looks like it will fit with some metal removal in front of the radiator and the hood has that clearance down the middle of it and that gives plenty of room for the fitting. The air filter box will fit in front of the radiator just fine. That will be really trick!
I wish you the best if you decide to go this route! It’s not real hard, it just takes a lot of work, and a steady supply of money! Just don’t get caught up in the "while I’m at it syndrome". Mine is coming apart later for that type of detail and I’m glad I did it this way because I can see what really need’s to be done, and I have gotten very familiar with the car so that should make it a lot easier.