I must have been looking in the wrong spots for custom pistons, most of the prices I saw were more than that. I think I paid $250 for the B21Ft pistons - incl. pins and rings. From what I had seen pricewise I thought I was paying about $400 - 500 less.

You are probably correct about the boost. If I were going to bother putting a turbo into the PV I think realistically I'd just get a later model B23 instead of expensively trying to do something to the B20.

I'm not exactly sure what the modified head I have is. I at first assumed it was a carb head because of the lack of injector ports and the small metal plate where the large idle air bypass widget goes on an FI head. But it doesn't look like a 'B' head - it has raised and machined injector islands. While I could imagine someone welding and resmoothing the holes in the intake ports, I can't imagine anyone filling in the injector mount bolt holes too. And the way the bolt heads and injector islands are connected (little machined bridges above both center exhaust ports) makes it seem like it is a late model F head. Maybe it was a late model Penta head? Makes putting fuel injection on it a little more challenging.