Records for the classes the '50 Chev would run in outside of the XO engine can be found here:

http://www.scta-bni.org/Bonneville/Records/BNIrecs_cat_c.htm

The 230-260 inch engines would be in "E".

Engine Classes

Letter Cubic Inch Displacement Approximate Liter Equiv.
AA 501 cid and over 8.21 liters and over
A 440 thru 500 7.21 to 8.19
B 373 thru 439 6.11 to 7.19
C 306 thru 372 5.01 to 6.10
D 261 thru 305 4.27 to 5.00
E 184 thru 260 3.01 to 4.26
F 123 thru 183 2.01 to 3.00
G 93 thru 122 1.51 to 2.00
H 62 thru 92 1.01 to 1.50
I 46 thru 61 0.76 to 1.00
J 31 thru 45 0.51 to 0.75
K 30 cid and under 0.50 and under