I did the lifter valley in POR-15 with a topcoat of their Pelucid which is a very hard clearcoat (although looking back, the Glisten PC might have been better...). I was looking for a very smooth surface and thought the Pelucid would do the job. I'm sure it won't peel or chip: this stuff just doesn't peel off!
Eastwood also sells glyptal which is made for lifter valley coating. I think that has been used more often than POR-15. In my mind, they are equal for the job.
www.prp-porstore.com and
www.eastwoodcompany.com