Prep the replacement A-pillar with urethane reducer. it will soften the plastic and help the paint to stick. If you really want it to stick good, use PPG's DPX-801 Plastic Adhesion Promoter. The only drawback is it is expensive since it only comes in a 64 oz can. You might be able to find a distributor who has it in a smaller amount. the 64 oz can is about $48. 00. Dse the disposable aerosol sprayers that have the little glass jar on the bottom. Get the paint from the dealer.
If you ever drive thru Beaumont, Tx PM me and I will meet you and give you enough DPX-801 so you can do several pillars. I even have some of the paint left over that I mixed at the auto paint store(agate).
Charlie