11:1 ford 302 compression

In your calculation, did you make an allowance for the valve reliefs. If you didn't, the calculated compression ratio will be higher.

The fact that the starter has a problem turning the engine over makes me wonder if the starter's performance is being affected by a low amperage output from the battery or the wiring isn't heavy enough to deliver the amperage to the starter. The ground wire to the battery's negative post needs to be at least the same size as the positive wire. Is there a good ground connection between the body and the engine? If everything is in order with the starter, it may be that the compression is high or the timing is too far advanced.

You at first mentioned that you had stock pistons then you say that you have the forged pistons. I would be hesitant in using stock cast pistons with a high compression ratio. I hope that you have the forged ones as the cast pistons won't hold up in my opinion.

Another question, did you account for the thickness of the head gasket? Most head gaskets are between .039" and .041" thickness.

I think that I would pull all of the spark plugs to see how the engine turns over. There might be a binding in the rotating assembly.

The old stock starters used an electro magnet system for the field magnets where the newer factory starters and aftermarket performance starters use permenent magnets and reduction gears. If the engine rotates OK without the plugs, try one of the newer small starters. They don't require as much amperage because of the fact that there isn't those electro magnets drawing a load on the battery. It should turn over an engine with high compression.

Watch out for too much timing advance with 93 and high compression and cast pistons. It won't take much to blow a hole through the top of the piston. Are you sure that you want to use your present heads?