The HO engines got front and rear sump pans with the front sump being much smaller than the rear on the later Mustangs. There may be rear sump 302's out there, but I'm not sure.
The roller cam was first placed into the Mustang 5.0 in 1985. The 5spd that year got a Holley 4bbl and a a roller cam. All Mustang 5.0HO's after that had the roller cam. The blocks are different. Slightly shorter lifter bores in the older, non-roller blocks, but there are conversion kits out there.
The 302 has weak main webs as well. The stock HO blocks with stock rotating assemblies will do fine with 450-500hp. Beyond that, you could lose it. Properly setting up and balancing the setup will allow you to stay cool up near the top of that range, and maybe a little beyond depending on your luck. There are stronger blocks out there for the 302, but they are hard to come by, unstreetable, or expensive.
Bore/Stroke is 4"x3". A common .030 overbore will bump the 302 out to a 306, not a 307.
