I would ask you if these pewter pieces are new or very old. Historic pieces of pewter should nbot be repaired or really even used. The value of these pieces as antiques is far greater than their value as an ale transport vehicle. Place them on shelf and enjoy them for what they are. Restoration, even done well, will turn a George III tankard into a piece as valuable as a dixie cup. Keep the old one and buy a new one to use. It will be safer to use as well.
Lets discuss pewter for a moment. Tin and lead allows were cheap and easily made in our early history. The tin was there to give some strength to the lead and there are probably a half a hundred different mixes of metals in pewter. Each caster had their own recipe for the metal. Strength was the factor. The big worry was lead. Now we know it was a deadly element for human ingestion. But back in the 16, 17 and 18 hundreds it was a major metal for eatting utensils of all kinds.
The melting points of tin and lead make it an easy alloy to work new but not very easy to work in repair. I have polished tankards and generated enough heat with the wheel to cause the metal to soften and cave in. Best to hand polish with a good jewelry cloth. Better still to alow the tankard to age and gain a patina that can only be had by use and age.