3 speed overdrive questions

[tjmeadows]

I recently bought an original, non restored 69 custom/10 pickup in good-average condition with a 307, and 3 speed manual with overdrive. Other than what few articles I have read here I know very little to nothing about this transmission. Here is what I know:
It has a 4 bolt side cover, not the perferred 7 bolt side cover
The housing number is 3744920 with r10k-1 on the tail shaft
It has a huge solenoid near the tail shaft, and a 4 prong plunger style solenoid on the intake and a cable mounted under the dash labeled overdrive

Here's the question, I'm leaning towards restoring this truck back to near factory specs, and i was wondering if the transmission option is worth restoring and how available are the parts? Does anybody know details on these transmissions? Seems that they originated in the fifties and best i can tell 69 was the last year for the option. Is the value difference of this original option worth the time/cost of restoring it worth it? Does anyone have one in a 69? Any help is appreciated, if i decide to discontinue this option in the truck, is anyone interested in the transmission, solenoids and cable?