99 grand marquis valve question
 

I had replaced the timing chains and guides/tensioners and such. Put the timing crank sensor on backwards and went to start it and it seized after throwing 3 valves into the pistons and completely breaking the valve heads off in the cylinders. I have the head off and inspected the pistons, which look fine but may need a quick grinding. I was wondering if the valve guides could potentially be damaged and if I need to bring the head in to have it inspected? I haven't pulled the broken valves out the head yet because I haven't bought the valve spring compressor yet.