return fuel line needed?

[77BBGMC]

I’ve done a search on this and I think I’m okay by not using the return line but wanted confirmation. Pickup is a 77 with a BBC, the original motor has a return fuel line. The mechanical pump that I put on the new motor does not have a return line. Do I just cap the return line? Will this affect anything?

My goal was to do this motor swap myself for the learning experience…don’t know what I was thinking! Guys on TV make it look too easy.