As mentioned already your compression ratio is now at the very least right at 12:1 assuming the combustion chambers are now right at 58 cc which you had said.

Just a tad bit high for an everyday street machine IMO.

 

Is there anyway to lower the compression without swapping the heads? What is a safe compression for a dd ? Should I be ok with a 12:1 with a good tune an lower temp thermostat?

 

I've seen f bodies run that cr on a good tune, but they are lighter. I'd say 11.5 would be a nice Target. Look at different head gaskets and figure our static and dcr.

 

running a thick head gasket will lower compression some

 

How thick of one would I need to get into the 11:5 range?

 

what gaskets do you have on there now?

 

Just stock replacement.

 

the stock replacements are .051" compressed thickness. You could get some of these in a .060 to take your compression to about 11.7:1 or .065 which will be about 11.5:1
Cometic Gasket - C5751 - Cometic Head Gasket 4.060" Bore - Speed Engineering Performance Parts

 

Tht would get me in the sweet spot right?

 

Have you been driving the truck around? I would do some lite driving and see how it does. But you would really benefit from some more free flowing heads.