Welcome back! I just got back into RC a year ago after a 13 year hiatus myself so Iknow exactly what you're facing.

Here's the drill for reviving the OS. Do NOT turn it over! Remove the backplate, head and carb and submerge the entire engine in fuel. Denatured alcohol is also acceptable. Cover the container tightly or the alcohol will evaporate. Let it sit overnight and it should start loosening Up. You may have to repeat this step a couple times to free it up completely. I'd also recommend completely disassembling and cleaning the carb as well. Oil everything up liberally when you're done. That's what I did with my OS 61 FSR and it's now powering my RCM Trainer 60 without a bearing change. If you need bearings, try http://rcbearings.com.

Radios - If you had decent radios, I'd just replace the batteries and use them. That's what I did. Check out NoBS Batteries for your battery needs.
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I'm afraid I can't be much help on the engine for the Dalotel. A lot will depend on the size and weight of the plane.

Jim<br type="_moz" />