just hauled out in SC last week and been there on and off for the last three years. surprisingly busy there, although summer will be quiet and HOT. 60 foot is at the upper end of the boats that I have seen hauled out in SC, but check with them. not sure about Guaymas limits.
in SC are very good. Although I have heard good things about Guaymas too. They have Singlar and the dirt yard.
I would guess for steel work that you will find more of the work can be done in Guaymas, although most of the worker come to SC. The machine shop in Guaymas is awesome and very reasonable. Hermandes.
It is cheaper in Guaymas for everything, but I like it better in San Carlos
for dinning and hanging out with cruiser folks. Although Guaymas is a great Mexican city with friendly people and SC is gringo land.