Transmission question

[4th Gen C-10]

I am going to be putting in a ZZ4 and 700R4 transmission in my 69 C-10. I know I need to get a new crossmember to go with the tranny. My question is should I get the engine and tranny/crossmember for a mock-up before I send the frame to the powdercoater or can I mark/drill any needed holes once it gets back?

Thanks

[ulakovic22]

You can do either, but I would mock it all up before hand so you don't have to worry about messing it up. You will probably have to clean out the holes with a drill bit after you get it back anyway since the powder will shrink them a little.