Bill,
A "roller" block often came with a flat tappet cam.
Here is he difference. The roller block with have a couple (three) threaded holes running along the cam ridge that goes from front to back of the engine right in the lifter galley.
The bore that the lifters sit in is also different.
If you remove the timing chain, there will be a machined circle behind the gear with a threaded small hole on each side. This is where the thrust bearing bolts down.
You have to have the type II roller block to drop the roller parts in.
Take a picture of the galley and shoot it to me or post it.
In later years, they put the roller cam as well as the roller block in the trucks. They were just converting everything over in the late 80s early 90s. Trucks came last
You will purchase the "rev" kit out of another motor, or new. I will consist of the lifters with the roller tips, 8 alignment blocks, and a sheet metal spider looking thing that bolts down to those holes on top of the galley and spring load holds the 8 blocks around the roller lifters to keep them from spinning. You will then need the thrust bearing and a timing chain specific for the roller cam.
This factory set up is far superior to any retro fitting of older blocks to full roller cams.
On a down note, that trans does not look like it is going to work well for you in this application. The shifter would be coming out way in the wrong spot, and it is so large around it would interfere with something.
You may be able to trade a salvage yard that HD trans for a 5 speed from a late 80s early 90s F body, or an actual later model six speed (trade plus $$).
The best part is, you already have the flywheel, etc. so that is a big leap forward.