Part interchange?? 289/5.0??Heads??

[shark7000]

I was reading here and there and was reading about how so many parts are interchangeable between the 289 and 5.0. My 289 is missing on a cylinder, since it doesn't burn oil, I'm thinking a valve job. I was thinking of keeping the 289. I have the 5.0 w/EFI to put in, but I've been reading about all the stuff I have to do to do the swap. Then I thought of something. How about the 5.0 heads on the 289. That will give me the roller rockers on the older 289. Then, I'm guessing, I need to swap the cam too. I know you have to have a roller cam for roller rockers. Would the push rods still work? Are they still the same length? Then use the carb setup. I have a Holley that needs some repair, but I should work good when it's done. It will still look pretty much stock, of course, I will be putting the T5 tranny in. It's already not stock. It came with the 3 but has a 4 speed. I will throw the headers in that came with the 88 5.0. This should help some on performance with the rollers. Right? Then I could sell my neighbor the 5.0 block, that he needs for his 83 Mustang.
The EFI swap was looking a bit difficult. I'm sure I could do it, but if I decided to go back to stock, I would have to repair the hole in the firewall for the computer connection. Plus other mods to be reversed. I believe the guy I bought the car from didn't use lead additive when fueling. I had this happen when a friend borrowed my truck, 77 Dodge Power Wagon, which was an original lead burner. He burned the exhaust valves, and I had to have a valve job done. I did have the hardened valve seats put it, but I think the head shop just gave me some heads that where laying around in the shop. The heads I got back had air injector holes that I had to plug up to stop the exhaust leaking and making lots of noise. They where not there before.