Ported PI heads are a great improvement over stock. The trick flow heads take it even further and really shine in the upper rpm range (biggest benefit can be made above the stock redline).
That being said - the stock PI heads work very well with forced induction / nitrous. Unless something is known to be wrong with the heads - I wouldn’t write them off at 150,000 miles. These motors are very resilient. The stock heads / cams have excellent driveability (you will lose some drivability with aftermarket cams).
With your current boltons and a 100 shot than your end result is going to be somewhere mid 300rwhp. The stock shortblocks are good to 400rwhp.
The question for your wallet to answer is that last 30-50rwhp worth the labor and cost of heads / cams.
I would take a good look at your long term goals- if long term you want more power than 400rwhp I would be saving up for forged internals plus heads / cams rather than putting on heads / cams on a stock shortblock.