just a few things to remember when doing an engine swap.
1. come up with a plan, think it through and commit.
2. whatever budget you project to your project, anticipate adding another 30-50% . the reason i say this is sometimes you end up buying something that is part of the plan and ends up not working, sometimes the plan just has to change. this is all going to happen and should be expected..... but a lot of that depends on the extent of the project.
3. if the plan you had isn't working out, it is ok to scrap it and think of another way to pull it off. better off to re think a portion that has eaten up time and resources than to beat the dead horse and do it wrong.
when i built Lucifer i spent money on 3 racks because the 1st one wasnt what i thought it was only to buy 2 more different one only to go back to using rack #1.
if you go atv motor expect that whatever donor motor you use will be in need of a rebuild. no point in stuffing some piece of craigslist crap in your awesome new build only to have to pull it out to rebuild it again.
good luck and i look forward to seeing your thread.