Put the trans in neutral. Parking brake off. Can you roll it? If not, you've got it jammed in two gears. Either your shifter/linkage is installed incorrectly (flipped levers, etc.) or the shift forks (internal, you'll have to open it up) aren't in there right and you're partly engaged in two gears at once.
Also, is this the original engine & transmission combination? if it's not the original engine, the counterbore in the crank may not be deep enough. Even though you said you put in a new pilot bearing (you said it went in tough), it may not have been finish machined to final dimensions- depth or diameter. If it is the original engine and not a replacement, I would suspect an incorrect pilot bearing. Too large of an O.D. being forced into the crank would cause it to compress, binding the input shaft. Parts listings (and the parts themselves) are sadly not that accurate anymore.
My two cents.
