318 head flow

As a comparison as to how much better the stock 308 head is compared to a 587 head.....
This was a nice low use 587 head, fresh 3 angle valve job, 1.88/1.60 tulip(stock) style SS valves with a back cut(no blending):

Lift———in/ex
.100— 60.0/ 53.5
.200—122.8/102.4
.300—176.8/129.3
.350—186.4/135.4
.400—188.4/139.0
.450—190.8/142.0
.500—192.0/143.2
.550—193.2/144.4
.600—193.6/145.6

An X head that isn’t beat to death, and isn’t plagued with some serious core shift, with a valve job and some 2.02/1.60 nail head valves can flow in the [email protected] range with no porting on the intake side.
Unfortunately, the ex ports aren’t any better than other lowly 360 heads....... sometimes not even reaching 140cfm in stock form.