TBH if the shock volume is wrong as it is, it’ll probably still be wrong post-PUSH, 2 different things. Spacers aren’t expensive and they’re easy to fit so it’s worth doing just out of interest (and can be replicated with grease, btw, on most shocks)
Only trouble with shock tuning is you really need to know what you want it to do. You can just go “make it better” but there’s no guarantee that the changes will suit you, it’s so much a matter of taste.
Also, if the shock’s not working right as it is, you’re not really working from a good base (I asked Loco to tune my RP23 for less initial resistance, he said “I could do that, but it’s ****ed, if I fix it you’ll probably be happy with the stock tune”. Good advice)
No one right answer I think. My old PUSH RP23 did work a little better than my current one, for me, just that bit more supple but still controlled. But ymmv.