Can i use roller cam parts in 81 block.

Steel1 said:

You could have the valley drilled and tapped for the spider tray and then use roller lifters or

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Ahhh, but is this true? After some googlefu that I did awhile back the answer is yes and no. Clear as mud.
Lets start with NO: (because it will help with understanding the YES)
NO: the non-roller block is not drilled for the spider that holds the dog bones that keep the lifters from rotating.
YES: you can have the block drilled and tapped for the spider but (and there it is!!) what about the dog bones? I have read that some have experienced problems with the placement of the bones and excessive wear on the lifter that resulted in failure. So this is a maybe?
NO: the lifter bores of a non-roller block are not as tall, a roller lifter is taller than a flat base lifter, this makes the lifter misaligned with the oil hole that feeds the lifter and you can guess the results when that happens.
YES: there are cam companies that make a 'small base circle' cam that will lower the lifter in the bore so the oil holes align to feed the lifter properly. But (there it is again) you have limited choices and can be expensive.
So, there it is in a nutshell. A muddy nutshell.
Of course the right way is to pony up for the link bar lifters, compared to retrofitting roller lifters into a non roller block is the correct way to go.
DISCLAIMER: this is from research done years ago when I had this question in my head and not based on any actual experience real or imagined.
Would I do the retro fit? NO
A flat tappet setup can live a long life if done correctly.