Grill Conversion? Please Help?

[TOYOTA61384]

I tried searching with no luck on exactly what I'm looking for. Here's the deal, I am looking to buy a 72 gmc sub, and hate the front ends, and would like to switch it to a 67-68 checvy style front end. From the research I've done I can purchase the new fenders, hood, and radiator support, but the front grill portion is not available. So I would need to find an original center grill section, correct? Is there anything else I am forgetting? Also how difficult is it going to be to get one? I've noticied some of you guys getting rid of them to switch to a newer style, are they redily available?
What else would I need?

Thanks Alot

(I'll keep searching, but I need to make my decision between two subs by tonight, or the latest, tomorrow night)

Robert