Depends on your area, but Growlithes are insanely common in the desert and 73% is very low IVs for most...so I'd say don't power up...Also, if something is very rare for you, I'd say doubly don't power up since you are wasting your hard to get candies...on a non-ideal mon.
I don't have a Gyarados yet (level 35+) and never evolved a Machamp till gen 2 due to hard to get candies...
I also believe moves and move power can change so investing in non-stab is a bit risky. Wild Charge hits hard and maybe useful for PvP, but I play for the now mostly...and don't care for PvP honestly.
Overall, powering up for CP and defense depends on gyms and CP in your area, but Arcanine can't get nowhere near enough now for me and many folks I'd guess. Vaporeon's are actually very rare in gyms as well now, esp for stagnant gyms.
The only way to use those is to be much much higher level than people around you (I'd guess 3-4 levels is enough) and you can use these other mons. This is hard since you'd be pushing level 38+.
Some stagnant gyms are also starting to be T-rex/Dnite gyms now.