292 or go to a 250?

[lovemytruck]

Hey guys,
Should I keep the 292 or go with the 250?
I have a 1972 C-10 I bought used. The 350 blow on the previous owner so he replaced it with a 73-83 ish 292. My trouble is there is no power steering pump or bracket. My gear box is power so I am left with this beautiful truck sitting in the drive and my wife asking me why I bought it if I is just going to set there. I found a 250 (73-83 ish also) that I could not pass up for the price thinking I would just chance them out. I can find a power steering pump bracket for it. I haven't been able to for the 292. This leave me scratch my head because some have said the 250 won't have enough power for the truck??? I don't have a clue. Also I will be taking this on 200 mile round trips a couple of times a year so gas mileage is important to me but I had truck that had to little power once and that is no good either.
Side note, If I run these without modes what kind of gas mileage to you guys guess I will be getting? thanks for any input.