Flywheel Help!

Alright, I bought a 331 stroker kit from CoastHigh last month. I also bought a 28 oz balancer and one of their 28 oz Probe Billet Steel Flywheels. Last night I tried to mock up the flywheel and clutch assembly.

First off, the flywheel came with no dowel pins and I have not tried removing my stock ones and see if they work, yet. Anyways, I tried bolting my pressure plate up to the flywheel. The flywheel is drilled several different ways for different clutch styles from different years. However, I lined up my clutch with the dowel holes and the bolt holes and my stock bolts would not thread in. I tried several different bolts and several of the holes, but none fit. I then removed the clutch and tried all of the holes, but again none fit.

My car is a 1993 GT and the pressure plate bolts I am using were the stock ones from the factory ( I assume). Is there a different size bolt for the 28 oz imbalance? I called Coast High but the guy told me he had never heard of there being a problem and suggested that I carry the flywheel to the hardware store and match up bolts.

Before I lug a flywheel into Home Depot, has anyone experienced this before? What about the dowel pins? Is there a kit that sells both? Thanks in advance!

Mustang5L5, thanks for the link. Is this a direct replacement? The issue I am having is that the stock size bolts do not fit my flywheel. I have read somewhere that some aftermarket billet flywheels use a different size bolt. Does anyone know if this is true?

Thanks again for the reply and the link, I will keep it in mind if it turns out I can use it.

Ok, here is an update. I tried the 5/16-18 thread bolt... no luck. However, if I flip the flywheel over and start trying to thread from the other side, it will start for about 2 turns before it gets too tight to turn. So, it is close.
I called Coast High, again. Got the same guy. He was still no help. We went around and around about the product before he tells me that I am confused and that Probe does not make flywheels. Uh... I point out that everything on his website states that they are Probe and that they are marketing them under Probe's name. He then tells me that they are RPM. Finally he says that he will call RPM and ask. Hour later, no call back. I call RPM myself.
Guy there tells me they are 5/16-20 thread count. GREAT... I finally have an answer. Except, someone tell me where I can find that thread count. Everything I have found is a 5/16-18 or a 5/16-24.
Also, now that I am looking closer at the threads, it looks like they are HeliCoils, not actual machined threads. I think I bought a piece of crap.

Anyone have any thoughts here?!