Base engine and tuning advice

[Madbaja]

So I’m after a bit of advice. I have a 1987 VW LT45 4x4. It’s currently running a D24 N/A. My plans are to up the power to around 200bhp. The vehicle weighs around 4 ton so wanting to make a reliable engine as apposed to pushing the limits. My questions are will the base engine be suitable or is there a better engine to start with. From what I have read the rotating assemblies are bomb proof so they will prob be stock but upgrade the pistons. Would people recommend changing to a later head and different cam? There’s also turbo and injections pump mods etc.
Cheers in advance