Is it OK to use the regular water pump with the 'newer' motor even though the old one has a HO one, or should I swap?

I don't plan to do much heavy pulling and it does have dual thermostats.

The important part is to use the right T-stat housing with the right pump. The HO pump does not use a bypass as it flows enough water and does not need a bypass block to maintain flow. The early engines need the bypass blocking type T-stat to maintain proper flow when the T-stat opens.

so pretty much that means that with your setup, no its not ok.

You should use a HO water pump anyway. Well worth the extra couple bucks.

Seriously. If you had a choice between the two, why would you NOT choice the HO?

The cooling systems are marginal in these trucks. Putting a non-ho pump in could cost you a engine$$$$$$$$$$$ I replaced the water pump in my 91 6.2 before i knew about the HO. Any time i towed anything it would run 210+. Not a good place to skimp for a couple of bucks. Also when i replaced the water pump on my 91 it broke the seal between the block and timing chain/ip piece. I got to take it apart a second time.[rework sucks hard]