Only two major challanges I'd say. First is fitting the trans and a correct trans crossmember depending on what you go with. This is the same issue with the LS stuff too kind of. 8 and 10 speeds require the tunnel to be raised (if its going in your 68). Second is the price of the dirvetrain itself. The motors and all are more than the LS stuff if you buy them new. Pullouts are cheaper than LS stuff though for some reason.
Heres a link to my 68 with a 6.2/10l80
https://ls1tech.com/forums/conversio...-v-swap-7.html