There are a few things that appear odd about this.

If it was an early 60's kit, it wouldn't have badges on the toms, bent floor tom legs, those type floor tom leg mounts. The rail tom holder and the bass mount cymbal holder are both old old stuff but the lugs and t's are newer. Twin legs on the bass?

I don't know. Something just doesn't sit well with me about this kit.

I'm not saying there's foul play. It just doesn't feel right to me.

The badges on the toms would put it at later 60's and the cymbal mount on the bass is definitely old school. 24" bass drums had double spurs, some 22's even had them. Were you able to see inside the drums to see if they are clear maple or chocolate milk or even mahogany. I'm not sure when they stopped using the consolette. The big tom is odd but kind of cool, it goes nicely with that big bass(if its a 24). I think its a cool kit. I would check inside that rack tom to see if it has holes for the setomatic mount. He might have put a diamond plate to go with the consolette. Get some pics of the insides and close ups of the badges.

The ride and floor tom badges are skewed, and the badge on the bass is lifted on the left side... so ....

I have a late 70s and a mid 60s Slingy bass, and the 60s has matching glitter inlays on the bass hoops, and the 70s has the "silver stripe stuff" inlaid in the hoops, if that might be a help..... I can't tell which is the case by the pic offered...

Isn't that a large tone control knob on the floor tom??? That'd make it late 60's, badge on the toms too support that. Slingerland to the best of my knowledge didn't offer curved floor tom legs, that was a Gretsch signature??Double spurs on the bass drum was common from Slingerland. Color seems to show equal discoloration throughout. Like Lucky mentioned, the interiors whether they're clear maple/mahogany or the weak milk chocolate paint should better nail the date down and there should be date stamps inside as well. This is definitely an odd set offering a lot more questions than answers. Play em', that's the deal maker or breaker, how they sound.

Regards

Dons