Couple of other ideas as I put same engine in SPF last winter. Guys above covered the hard part.
A shim was required under one motor mount, passenger side I think, for engine to set square in engine compartment. Shims came with engine mounting parts assortment from SPF. We removed and flushed
oil cooler and
oil lines to be sure that there was no debris in cooler or lines. (I wish we had done this on the first install, long sad story) We experienced same problem as Mr. Fixit with side pipes clearance on passenger side. We did not use spacer and solved problem by opening up hole with die grinder and a little touch up paint. Otherwise shoving a 428 in there was easy less a few scraped knuckles. Good luck!