Professional Products is the balancer you need. There is no spacer necessary if running the V-Belt setup. It will work with a 3-bolt setup. Spacers alloy you to run a 4-bolt serpentine setup if you choose to do so in the future. They are rated to 6,500 RPM and have timing marks for early and late model pointers. SFI approved models are also available but not necessary if you rarely see 6,500+ RPMs.
Here is a
link to a 50oz. damper. The same company sells a 28oz. damper as well.