So this got me off my lazy ass and I just ordered one of the guages off ebay. Its part number 19122:
They are available through various vendors both new and new old stock and the prices vary. I made an offer and got one for 9.50 shipped, but looks like about $11/12 is the norm on ebay.
Heres how you use it/quote from the manual (the visual in the book is helpful, cut end goes into the guide)
"
Service 1/4” (6.40 mm) Valve Guides
Model Series 60000, 80000, 90000, 100000,
110000, 120000, 130000
If flat end of Valve Guide Plug Gauge, Tool #19122 (1),
can be inserted into valve guide a distance of 5/16”
(7.92 mm), Fig. 10, A, the valve guide is worn and
should be rebushed."