Ok, from the photos...
The date code on the block appears to be A129, correct? (I couldn't tell for sure from the photo if the last digit was a "9" or an "8"). If it's a "9" that means it was cast January 12, 1969 - making it a year model 1969 block. (A128 would mean January 12, 1968 - year model 1968). 9790071 is a 400 - some had 2-bolt mains, some had 4-bolt mains depending on the application.
The "WS" indicates (if year model 1968) 400-HO GTO - 4 speed, 2-bolt mains, or if model year 1969 it would be a 400 Ram Air III - GTO - 4 speed, 2-bolt mains (but if 1969 the casting number for WS RA-III should be 9792506, not 9790071, so hopefully that block date code is really an "8").
The head date code, B068, indicates February 6, 1968 - again model year 1968. For 1968 HO the tops of the center exhaust ports should have "16" on them.
Ok, compression ratio. First of all, don't go by the factory published specs for compression ratio. The published specs were based on an engine that had been "blueprinted" - i.e. everything machined to minimum/maximum (whichever was most advantageous) factory "blueprint" engineering specs. Such a block would have been zero-decked, the heads milled so that the chamber sizes were at the engineering blueprint minimum - and would have been 10.75:1 compression. The engines that rolled off the assembly line wouldn't have been zero-decked (probably closer to .020 down) and the heads would have been "about" the nominal chamber size of 72 cc's - and would have had a compression ratio of around 9.8- 9.9:1 That's one of the reasons an NHRA class-legal "stock car" is so much faster/quicker than it's street-legal counterpart. Its engine has been built to 'factory blueprint specs'.
To be 'safe' with a factory (or factory spec) cam on today's gas (93 octane) you'll want to aim for a compression ratio of less than 9.5:1 ---- probably around 9.3:1. On a "nominal" 400 (stock bore, stroke, .020 deck clearance, .045 head gasket, 6 cc's in the piston valve reliefs, 72 cc chambers (ALWAYS measure them!) ) I'd recommend swapping the pistons out for a set with an additional dish in them such that their total dish volume including the valve pockets is around 12-13 cc's.
Especially on a street engine, pushing compression ratio to the limit doesn't help power enough to justify the risk (in my opinion). On my 461 that's making over 500 HP, the difference between 9.5:1 and 10.0:1 would only be worth about 8 HP, everything else being equal.