I bet you $100 that your motor doesn't last 500 miles. Not just because he may have gotten rushed at the end, but because if he hasn't built any buick motors before (I'm guessing since he had none of the equipment needed this may be his first) this one isn't going to be right. Hell, even the ones I had built by "professionals" were wrong.
I also cannot understand how paying $2800 was cheaper? Who was more than that? Christ, thats the highest I've heard of considering he didn't provide many materials.
Better check the clearances all over, and endplay.