Heater motor clearence

Have 73 Duster 6cly, my plan is in the next couple of years is to put a 440 in, so I will be lining up parts to make the swap.
My question is the clearence between the heater blower motor and the valve cover, seen alot of A-Bodys pics on this site that looked like they had lots of clearence when i thought it was a trouble area or concern. Iam sure there are some TIPS to get the clearence.And also my car is a colum shift automatic will there be any issues in that area.. Thxs folks FBO Rocks