John, I have been considering tunes for my 36 for a while and have done some research, If you are installing in the Glovebox anyway, appearance of the unit is less critical. I tried looking up the USA230(?) radio you mentioned in another post and it looks pretty expensive. A few other alternatives I found are
http://www.amazon.com/Pyle-PLMRKT12BK-In-Dash-Marine-Tuning/dp/B002J9GHHA
http://www.amazon.com/Pyle-PLR14MPF-In-Dash-FM-MPX-Shaft/dp/B004HJ3FH0
Both a lot less expensinve and the one in kit form even has a remote and marine grade speakers.
Post back on what you end up doing, I'd love to hear what you think of the final result
Power converters are available on Ebay for the 6 to 12 volt, positive to negative ground issues if you are still running 6 volts
Matt