Sir, Suhaib Kiani saheb's knowledge can not be challenged,...... but
1 PZ is a normally aspirated engine, if I recall correctly. It is a relatively robust engine, with characteristics similar to but a lot better than the 3L series, I think around 100 horse power.
1 HZ on the other hand, is a very powerful, Turbo charged, high speed engine, around 165 horses. I think it will be reasonable to check on the specs, because if there is a lot of difference, then the pleasure of driving will be decreased.
1 suggestion, though. If the 1 PZ is OK, why not continue using it? 1 HZ is mainly for high speed cruising on highways. The leaf spring, short wheel base vehicles, typically the BJ 70, 73 series, on the other hand, are not meant for extremely high-speed driving, and for off-roading, I don't believe, 1 PZ will be lagging behind any other vehicle.
You have a beautiful vehicle, Fobak. I like it.