I am new to the kit building and have been flying foam planes for just over a year. I have inherited a 1997 "FUN SIZE" P-19 ( 59" wing span) that was partially built. This was designed for gas but I have been reading stories about dead sticks due to engine stalls and am curious if I should equip this for electric? Fuselage is only about 30% done at he moment w/no servos or wiring. Thought???

By gas I assume you mean glow powered. If the fuse is still open then you can make it electric more easily as in creating a battery hatch, etc... Glow engines and the new small gasoline engines run well when properly tuned and maintained. You can still have dead-sticks with electrics ! Glow requires more field equipment than electric however electric has a higher cost initially with the larger batteries. A lot of folks have electric, gasoline, and glow planes while many choose to stick with one type. It really depends what you want.

Is one more advantageous than the other? Along with the plane, there were 3 glow engines. How are these tuned? Does not look like there is much to them. I like the sound of them but have no experience.

More advantageous? Again, it depends where and with what you are starting out with. First you said you have a partially built plane , now it's a plane with 3 engines. What else do you have ?
If you have all of the glow engine support equipment like a starter, field box, glowstick, tools, etc..those are things you won't have to buy as opposed to buying electric batteries, a good charger, and a 40 size electric motor and speed control.
A 2-stroke glow engine requires some experience to properly tune it and keep it tuned in different flying conditions. It's not overly difficult and it becomes second-nature after you have done it for awhile.
Your best bet is to find a local club and/or someone who has flown glow engine planes and have them look at your engines and they will tell you if they can be used or not.

My personal opinion only: I flew glow since the early '60s. Tried electric about 5 years ago. Traded all my glow and gassers for electric, and never looked back. For me electric has so much less hassle, cleaner, quieter, and way less maintenance. Only downside I have seen with electric, is spending time charging batteries before a flight session, as I prefer to charge at home, and not at the field.
On the other hand, if you have only been flying electric, you might look at this as a chance to explore glow power, and see how you like it.

I tell people that are just starting out that electric isn't a bad idea but the start up costs can be steeper then glow. I have friends that have never figured out how to set up and tune a glow engine, one friend had gas and glow and sold all his engines and went all electric, even with his giant scale. I have no problems with dead sticks in gas or glow and have all the support equipment so going electric for me would be silly, I do have one small electric.
If you don't know how to tune a glow engine it's best to have someone teach you, even then some people can never figure it out.

I have all three, gas, glow, and electric.

They're all fun. Just pick one. LOL

If you do have desires to move to larger models, in the 100" range, I would suggest that you choose glow or gas, however. The expenses incurred with large electric models may be prohibitive. They sure are for me. LOL