Rear leaf spring question

Im considering new leaf springs for my 68 Valiant(360 orig /6)
The V8 springs have a 5/8 bolt front bushing, While the /6 car has a 1/2 bolt bushing.
I have the 1/2" bolt bushing. Can I drill the spring pocket to 5/8 or is there anything else to consider.
At general spring there is a 50 dollar difference (the 5/8 being less expensive). otherwise they appear to be identical
Talk to them at General Spring, they can tell you the exact size bit and set you up with all the hardware too.