5.7 mounting question

[Larry S]

I have a 1996 5.7 engine I am trying to place in my 71-72 frame. I tried to set it down in the frame today, and the stock manifolds hit the frame before the mounts will sit down on the mount stands. Ive never tried to put a vortech in this year truck but know it can and has been done. The mounts look like they will line up if the manifolds were removed, allowing the engine to go down. Also what crossmembers will need to be removed, relocated or added to accomodate 5.7/ L460e? Thanks for your time!