Hard to say for sure as there were many different Sovereign models. Mine is a ply top but the good ones are solid. The one in question is likely a 25.25" scale though there was some variation. Original retail prices appear to be ranged from 100 to 175 dollars give or take. I've seen good examples go for triple that in Canada. I would suggest watching eBay for a better indication of price.

Cool funky guitars, great vibe.

Peace, Mooh.