At 66k miles? I'm a little heasitant. If it was 100k+ I'd be game. How much has it run you to get it done?
Most valve springs are down 1/3 of their rate by their 5th birthday running them or not. (Biggest weakness in buying a crate motor, a few of those springs have been fully compressed since the motor was built...)
By comparison, the sprint car I take care of the springs are replaced each season, that's like 12 hours of runtime... BUt at 9000 LOL
If you take the head apart yourself, and take the bare head to a shop a boil out is like 20 to 40 bucks.
Valve springs are a few bucks, set about 140.. Your stock ones can be bench tested at a machine shop for probably 20 bucks... Or if you have a high school with a auto shop I've hit the teacher up to have a student test them for me and made a "donation" to teh shop fund...
Valve seal kit about 20 bucks.
If I pull a head I have a shop check it for straightness and maybe have them hone it .005 just to open the surface up for being re-seated on the engine. Not a big deal... if you don't have that done, make sure the new metal is lightly sanded to open the pores of the casting back up for the sealant on the new head gasket.
CHeers
Dave