Here's some formation that I posted about the rifles awhile back in response to a similar question:
"There were actually three variations of economy Winchester bolt action rifles based on the Model 70 action produced in the early post 64 years.
All original Model 670 rifles had the two position Remington style trigger mounted type safety. A total of approximately 287,000 of them were built between 1966 and 1979. One interesting chambering for these early rifles was the 225 Winchester cartridge. In 1972, the Model 670 was supplemented by the improved/upgraded Model 670A which had/has the traditional 3 position safety.
In addition to these two, the Model 770 was a middle grade rifle produced from 1969-1972 with production totals of approximately 21,000 rifles."
So if you have the original Model 670 you'll see similarities to the Rem 700 with the safety. If yours is a newer Model 670A, it will have the traditional side swing 3 position safety mounted on the bolt shroud.
Either way, its not a bad choice probably to build from depending on what you want the outcome to look like and how you want it to function in total. But either one is probably not a first choice of most builders either for a custom since a true push-feed post-64 Model 70 is not that much more expensive and they are readily available in good condition.