how hard is the ls1 to swap in? i have replaced a 305, it was a pain but not to bad. is it alot harder to get the motor to fit? 383 vs ls1 price and long term engine lasting is a concern.

 

the 383 will bolt right in and use all your factory accessories, engine mounts wiring ect.

the ls1 will require aftermarket motor mounts, maybe a k-member, different trans, trans crossmember, you probably cant use any of you accessories, you have to re-do all the wiring and use the harness from a 4th gen f-body.
Its a LOT more work, but they results can be very impressive, if you have the knowledge to complete the job.

 

I'm finishing mine up this weekend, been working on it for the past 3-4 weeks off and on, it is alot of work, but I would have to say more time consuming then anything else, also you can make a stock LS1 with heads and cam or even just the right cam and boltons out perform a 383 and you'll still get 25 MPG Highway, let's see that 383 do that, I also have a 98 Formula LS1 and love it!!!! All in all when you look at it, it's all just a bunch of nuts and bolts.

 

You don't have to swap the k-member, you can bolt a 700R4 up but 4L60E is a better choice or 6-speed (don't have to swap the tranny crossmember with an automatic, only the 6-speed) There isn't alot of wiring that needs to be done, around 8-12 wires total to hook up and will have as much HP as a 383, and with a cam more power and like diablo said, 25-29mpg on the highway.