Are books available that can identify motor parts from casting numbers,the reason I ask is I am wanting to research cylinder heads for the FE motors. I have a 66 390 in my 65 country squire that was originally a 2bbl motor that has too much compression to run any gas less than premium,I have richened the carb and lowered the temp of the thermostat and it will run great on premium but since the gas prices fluctuate wildly I would like to get this motor to run on mid range gas and possibly regular without sacrificing too much of its power. I am tring to find a set of heads that have a little more of a combustion chamber to slightly lower the compression but not run as poorly as the 360 I have in a 70 F250 that will run on any gas. I am not worried about finding heads that are already setup for hardened seats as I will have them installed and those heads probably will lower the compression too much like on the 360.