[Dragsinger]

Dan,

in no special order, a list of some things to consider, all are small in consideration but add up when combined

*is one body more aerodynamic than the other
*does the combination have a wide range of available parts
*does one package have a proven winning record over the other
*does the chosen body allow several engine combinations, thus allowing options for other classes
*consider the suspension, "generally" a leaf spring rear, a-arm front is well worked out with the older cars
*is the chosen engine a package you are familiar with
*does it have a carb you can work on
*do you fit well in the car, will it be easy for you to drive
*and of valid consideration, can you find a good core body and the required class specific engine parts
*do you like the appearance

All just food for thought