Cylinder heads
 

Please don't shoot me if this is a silly question Does anyone know the difference between a b660 and b61p cylinder head?

Iirc the b660 was from the turbo 323.

fwiw I found this.

some of the early heads were somewhat different. upper front and back exhaust flange studs were in a different spot some others had spots for ether or stud locations. also have seen 323 heads some with a freeze plug in the front hole where the Miata thermostat housing bolts but still being machined for one to bolt on and others without the machining just a hole with a freeze plug.

That is a ton of handy info.

Thank you for the information,
I'm asking this because I have changed the engine on my mazda 1989.
It was a short nose crank with a b61p cylinder head, but I managed to find a early model model long nose crank engine. But it's got a b660 cylinder head, I don't know the car feels alittle flat compared to how it was.
luckily I have kept the camshafts off my old engine.... Is it worth changing them over?