Go to this page, the NHRA Stock Car Classification Guide, then click on 1968 Chevrolet:
http://www.nhraracer.com/content/gen...635&zoneid=132
That will list all legal combinations for 1968 Chevrolets for Stock Eliminator.
WHen you see this
327
*
250hp
12.88
One * is the Stock Eliminator rating; two ** is for Super Stock. 12.88 is the weight break for the car, which would be J/S with a four speed, and J/SA with a Powerglide/automatic.. A car can move up (I) or down (K) one class, with weight changes. Top weight break (12.00 for I, 12.50 for J and 13.00 for K) x the NHRA Rating of the engine (that 250 hp version 327 I listed is NHRA rated at 245 that you see when you scroll to the bottom of that column) + 170 (driver weight; all cars use 170) = minimum eight, with driver, across the scales at the conclusion of the run. So for J, 12.50 x 245 + 170 = 3,232.5 pounds for J/S-J/SA. You figure the weight the same way for I and K, using that Class' weight break.
For engine specs, camshaft, compression, valves, etc etc, refer to the NHRA Blueprint Guide, at
http://www.nhraracer.com/content/gen...634&zoneid=132