From SDC Forum : April 2014
(http://forum.studebakerdriversclub.com/showthread.php?80225-How-do-you-know-you-have-R1-heads)

Ted Harbit:
     The R1 and (R)2 springs have 9 coils and standard springs have 10. The valves are the same size in all V8 heads from 55 through 64 except for the R3 and (R)4 engines.


StudeRich:
     The R1/R2 Heads will have different Valves as well, they are the H.D. Stelite tipped valves.
     They are bright Silver, not dark gray steel like the Std. 259/289, but of course that is assuming the valves are original.
     The bottom of the heads of the Original exhaust valves are not "bowl" shaped or completely flat like Std. but flat on the outside with a recess in the center. 


R2Andy:
     Cylinder heads with the 1557570 casting number were used on all '63 and '64 259 and 289 CID engines with the standard compression ratio and on all R1 engines with the standard compression ratio. 


Warren Webb:
     I'm surprised nobody has mentioned the spark plug openings are machined to accept different spark plugs too or am I mistaken? Avanti engines are listed as using J-12 Champions vs. regular 259/289's call for H-8 through 14's.