Rich ,
I used the Gibbs BR on three engines I built, because my machinist recommended it. I have had good luck so far breaking in the new cams. I think the low detergent factor is probably the reason it is not for long term use.
I , used the Castrol GT in my boat engine for years , so I was interested in this Classic. I like Amsoil too but it is pricey.
My stuff sits a lot too Rich . This engine sat on the stand for 10 years , and I finally decided to put it on the dyno just to do something with it ! LOL
Thanks !
Mark