Zul8tr
you said
"Higher exhaust porting yields less static compression pressure because less cylinder volume from TDC to top of port. Most stock 2 cycle outboards are about 6.5 compression ratio (CR) relative to top of exhaust port, if you raise the exhaust ports that lowers the CR relative to exhaust. "

to counteract the raising of the exhaust port (40 thou) many things have been modified.
The idle reliefs have been closed off ? this should raise compression.
the head being skimmed ? this should raise compression.
and the combustion chamber itself being reduced to about 2/3rds its normal size ? should dramatically raise compression on its own..
these 3 factors should of raised the compression to far exceed that of the OMC SST60.

I think another known to be reliable compression gauge would be a good idea to know what is realy going on, simply because 145 psi is not
even close to what is considered a high compression OMC 56.

I would of been expecting atleast 175 psi, then bed in and make around 180 to 190 psi .