Aftermarket core support RANT!!!

[BubbaGreen]

I have a replacement aftermarket core support for my 71....and have some issues with it and would like to hear from others there experience.
1st, the lower radiator mounts had the weld nuts welded inside the supports, ok, no big issue, ground the down so the rubber inserts would fit.
2nd, went to mount the upper radiator brackets and the drivers side weld nut is not center correctly, ok, enlarged the hole for that radiator bracket into an oblonged pattern and that fit.
3rd, went to mount the battery tray (that fit perfectly on the stock core) and using the pattern on the aftermarket core, it twisted this tray into an unlevel trapazoid. The 3 weld nuts that are closest to the radiator are welded in, in such a manner that they dont run parallel to the core, but follow the bow of the support....I either need to redrill the core -or- redrill the battery tray -or- get a GM replacement core....
I havent even attempted to put the brackets to mount the fenders or fender wells...also, I dont see the weldnuts to mount the charcoal vent canister.
If anyone can recommend a good brand -or- actually has used a GM one, Please comment. Thanks!!!