Best way to check is stick a compression tester on it. Where did you get the seals from. I got some patterned ones from a place near me and not had any problems at all.

I thought if the rings were worn you'd see smoke when you let off and on startup. If the rings were badly worn you'd get constant smoke.

To be honest I have got parts from Ford before but alot of parts they sell are made by someone else anyway and Ford just put their name on them. I had a quote from them for a set of genuine Ford pistons (Mahle) £400+. I got some Mahle pistons from a local engineering place for £300.

Cheers
Dave