I am wanting to find out what I have to do if I want to stick a roller cam into a 84 305. Anybody know if any mods have to be done to the block or is it a straight drop in?

 

It is a direct drop-in, as long as you use the system that worked so well for all of us who had been building roller motors for all those decades before the factory did what they did. I think they must have accidentally got their summer intern's sophomore engineering project mixed up with real drawings, and by mistake started building that twisted bizarre Farnkenstein of a mess that they created; why on earth they did something that required new block castings, new timing gear designs, new cam designs, etc. etc. is beyond me.

All you have to do is use what is now referred to as a "retrofit" cam, lifters, and cam button; and usually shorter push rods, since roller lifters are usually taller than flat tappets. No modifications whatsoever to any other parts at all are required. It's just too easy.