Check out the Eastwood catalog and video and take a look at what they offer. DTM Epoxy Primer - Paint Primer - Automotive Primer Paint - Auto Primers ? Eastwood
Many of the standard type primers are not sealers, so over time moisture can/will get to the metal. Sometimes after a prime with the standard spray bomb, I use a top coat spray bomb to seal it knowing I will be sanding it off/down prior to final paint. Self etching epoxy sealers are probably what you are looking for. I have used them, but not let the parts sit around as I was usually at that point ready to color paint.
HOWEVER, it seems the EPA has reformulated spray bombs and they do not work like they used to. Once you paint and let dry and then go for another coat, the new coat has a tendency to lift or wrinkly your nice previously painted coat. I have tried many brand paints and techniques using spray bomb with not so good results. Best seems to lay down the first coat, give it about 5 minutes, put on a second coat, another 5 minutes and third coat or clear. This is by no means a guarantee of a quality job as the paint can become heavy and sag/run, or the infamous lifting/crinkling. Very frustrating to say the least. Then with 2-3 coats of paint, seems like it takes a week or more to fully cure. True automotive type paint with the hardeners are probably the best route, but you need all the equipment and it costs.
I am telling you this because you want to get a primer, or any top coat, which will not be affected by your finish paint coat when you go to paint your car. Hate to see you have the top coat lift/crinkle the underlying paint that you used to preserve you sandblasted part. When I used to paint cars in the '80's, I always put down a non-sanding primer sealer over the whole car to lock in the primer or old base paint prior to spraying the top coat/color coat that the car was to be. All I had to do is run a scuff pad over the primer sealer to give the top coat a little bite and remove any dust/overspray. Never had a problem, but that was the "good 'ol days."
So do a little searching, hit Eastwood up with an email/question as to your needs and their suggestions, and go from there. You only want to do this once as twice will be costly.