So the other day the ls1 in my 99 z28 **** the bed. and spun a rod bearing .. im not driving it anymore and its my daily driver. ive looked around and seen 5.3s and 6.0s as a decent replacement engine. ive found an lm7 5.3 in my state for 500 bucks complete with all the front accessories, wiring harness and ecu with 80k miles. to my question what will i lose from the swap as far as horsepower and tq. is it all direct fitment? tranny too? will my ls1 headers fit the lm7? i just need to get my car back on the road... let me know, thanks

p.s. i plan on rebuilding my ls1 with all the goodies for next year