12valve engine

I am looking at putting a 12valve into my humvee project that i have and need some advice. I have found quite a few engines with the rotary pump for sale and not many with the in-line. Can decent power be made with the rotary or should i hold out and keep looking for an in-line pump motor. I have found a couple of nice engines for around 1500.00-2000.00 that are all the rotary pump. Most of them have over 200 thousand on them. Should i worry about the mileage or using that pump? Not a great selection up here in Wa st.

Any advice would be great from the guys who know the engines as i am new to the 12valve and only know what i have read so far.

Thanks

Todd