To have a 'profesional' mechanic go through it is all very well & good.
But don't forget it's 50 years old & S#*t still happens.
Possibly best to still carry on & try sell it for a good price & i'm surprized it hasn't gone to a collector already.
Was it listed on Ebay or Facebook--or somewhere.
The ballancer & components would be what was removed.
If the parts are still around a buyer might want them including the oil pump for orignality but maybe not to fit.
If ya run it just keep it plenty oily & plenty rich in the carb settings.
95 bore [or 96 if max oversize]. Its a big bore. YZ490 [500] is only 87mm by memory--because it goes up & down further.

RT325,

As I mentioned on a earlier post, only scammers and people who want to get the bike for next to nothing were the only ones who asked about it. So therefore, it's not worth it to try to sell again. But instead....I will have it fixed and put new seals in to help- make the bike dependable. It has been rebuilt by the previous owner so all of the bearings, crank, bushings should be all fine. He did tell me he removed the counter balancer and a few other not so dependable components.

I hope I can sell my 1969 DT1 250 once I get the lighting hooked up because my mechanic is retiring this December since he worked on bikes like these for over 50 years. The proceeds will help to make this beast the king of the desert!

If anyone reading this post would be interested in a restored 1969 DT1 250 with title/current registration + original black and yellow plate, please private message me and will put you in line for this bike. 

Arin

Here's one with lights fitted. Now that brings back scary memories as fitted lights to our shop one to help sell it as an enduro bike after a season of motocrossing.

 

Ok, sounds like you have the best man on the job so that's good.