Engine Block code

[69SCSS]

I have a 292 in a C20 I'm working on and since it's a 65 I know this engine prob isn't original, since it has a monojet on it. But, just wanted to find out what this actually is. Here are the numbers on the block:

35 88
GM 4.8 G
93411147

M0220PTA

Head stamp: 4886F8

I have figured out from research it's probably a 75-84 block from the casting #, and the date code tells me Feb 20. Not sure what the PTA is, it didn't show up in the chart.

Thanks in advance for your help!

Any ideas?