So I am going to either rebuild my 292 or swap a 350 into my 68 c-20, but which?

I have seen a few 292's that were "warmed over" with plenty of aftermarket goodies...but will a stock 350 make move hp for a longer time?
Are the parts for the 292 more $$$?
If i move to the 350 will the stock tranny take the extra hp?
I plann on keeping this truck for quite a while as my work / toy pulling beast, but am not sure which direction to go in.
Help? :confused: