Considering how similar our boys are, I don't think you'll have a problem. Your guy seems to be used to going after his food at his own pace anyways so I think he'll go for the rat.
If it's any encouragement Tappy took his first rat no problem and he may be a striker now! I'll have to see if I can get a repeat of this for his next feeding, but for his very first rat he struck from his hide and dragged it back inside, something he has never done before!
I did thaw the rat and his usual mouse together in the same ziploc bag overnight in the fridge, and again in warm water so that may have helped. But over all I did notice rat had a stronger smell. So that may have had influence.
So for your guy I'd say hope for the best but be prepared for issues in case they happen. I'd be sure to still have back up mice for mixing scent purposes or in case rat doesn't work out. So for how much rat pups you wanna buy it's really up to you but 1-2 month supply sounds like a good start to see how things go!
Wishing you the best of luck!