What kind of bike? Dyna,Bagger? If its on a jack I would not try to install it as one peace. Ive done it both ways...on a lift. If your going to mussel the motor in hole I hope your a strong MF and have a good back lol. seriously though, If its a bagger I sometimes assemble the rear cyl,head rker box as its sometimes easier. You need to have the trans lifted (strap or jack) in front so you can get the hole motor in. Its a big pain putting a assembled motor in. If its a Dyna assemble it in the frame. much easier to assemble in the frame. others may do it differently. Good luck
2001 FLHTC Custom built 117ci (Mr reliable)
2001 FXDXT (S&S SA 126ci motor) 136hp 137 tq
2010 street glide..103ci 57 cams...fun and reliable...