What's the compression height for a 360 magnum as buying pistons

If you deck the block down .010" then these may stick out the top a tad. Not a killer problem but the installed height would be .005" below a 'nominal' Magnum block height before any decking.

If you you deck the block to where these are right at deck height at TDC (zero-decked), then your Static CR will be right around 8.1 with a .040" thick head gasket. Looks like a decent choice of dish size for boosting.

Don't worry over the 'stroker' item.... these compression heights are right. I'd worry more about the descriptive hype at the bottom, with the repeated use of the word 'extreme' LOL. I don't know a thing about this company, good, bad, or indifferent.