A little advice on this Formula purchase.
 

I have a deposit on a 1991 SR-1 29' with 156 hours and has been stored for 10 years. It is all stock with 502 engines in and I paid $17,500. for it. It is about a 8.5 condition. All thing I should be aware of when deciding if I should purchase it? Thanks for any help!

change oïl in engine and drive, change water pump impeller, some good gas, sparkplug, should be good to go!

And thing odd about this model? Is a popular one? Also what is the difference in the 502 verse a 454?

502 was 415 Hp. 454 mag was 385hp. If it sat for 10 years you may have some dried out seals to deal with too.

The 292 is a great model!! And you will really appreciate the 502s over the 454s because of more power... Formula boats are built extremely well which equates to a heavy boat!

Was it stored indoors?

After sitting for 10 years I would add to Jeff's list of must do's: Rebuild the carbs, dont even waste your time tinkering with them... change ALL fuel filters, distributor caps (points most likely got rusty from sitting for so long), 2 fresh marine batteries

Drive and shift Bellows ....while the drives are off ...grease the universals ....

Yes to all of the above. I would think it is a HEI for a 1991. I don't find many of this model around, the 272 seem more popular, any idea why. Seems like guys are saying that the large boats are cheap, just wondering if the age and model is a problem? This one was stored inside.

No model issues .... The SR is probably the best formula has made ..... it is 22 years old and it is a boat. ... great boat you won't be disappointed ....

292 are a great setup, 502's will get you darn close to 70, its was a middle boat most jumped from the 272-311, I almost bought the one currently in the OSO classifieds pretty sure your looking at the twin in NJ based on your description, as said above a thorough maintenance is needed, hopefully this thing was started once in a while, I would stock up on fuel filters and change frequently until you get to a comfortable point,

There are two different versions of 454--the base engine which has peanut heads, cast internals and puts out 330 hp at the crank (not really upgradable). The 454 mag has rectangular heads, forged internals and puts out 365 hp carb or 385 fuel injected. The 502 is identical to the 454 mag in that it has forged internals and rectangular port heads. HP is 390 carb or 415 fuel injected. Supercharging or adding a blower should only be done with the 454 mag or 502.