Installing the new converter today, and when bolting trans back up, it does not feel like is on all the way. I pulled the trans back down and it seems as if its all the way on. But with the trans bolted back up the converter is very tight and wont spin to get to bolt holes. Any tricks in getting these damn things in

 

The converter should slide back aways when on correctly. Sometimes a performance converter may be a little "tighter" and it could be from a tighter machining tolerance.
When my converter was completely on it sat off the flexplate aprox.1/16 of an inch. When I bolted it up, then did it come forward ever so slightly.
Let me tell you what WILL happen when it is not on all the way, learn from my dumbass mistake with my 86 Monte SS.....
....while trying to get it together I didn't think much of it that the tranny and engine did not come together just right. It was approx. 1/4 off. I figured the the bolts would pull it tight. The converter was pretty loose and would fall if I bumped it dropping the engine in. I had to readjust 3 times so... I figured this time I got it. I bolted the engine to the tranny and had a hell of a time getting my converter to mate to the flexplate but I managed. Every thing was fine and after aprrox. 250 miles I suddenly lost engine oil pressure. Pulled the oil filter and it was full of bearing material. The pump was clogged full. It seems the pressure from the tranny forced the whole assembly forward and it ate the thrust side of the bearings. The flex plate was bent from being forced on.