I would take tranny out. Engine too heavy to "shake" splines in. But I have never tried putting engine in that way. Seems like potential for heavy swinging thing to damage lighter solid thing. Not a lot of work to take it out.
Secondly: Built two years ago and sitting? Not sure if PO did it right? Seems hard to turn over?
Should put on engine stand, drive oil pump with drill to check flow and pre oil. Turn over with starter, no plugs, to see if starter spins it good. Would be nice to start it, if you can, on the stand. Have an experienced person look and feel and listen. ALL this BEFORE installing. You need to know what start-up procedure the 216 guys do after rebuild. Can't gauge how hard it is by your description, could be normal, could be trouble. Be careful. HOLD OFF....See what the 216 boys say to do.
