hellblazer set 55 set has 75% crit dmg boost and 30% coup de grace boost but it isn't better than 65, 65 is better.
Even though 65 gets only 40% crit damage boost you get 20% more sword damage which works for everything as well as 10% more hp and more def/mdef than 55 set.
At 70 i remember with just the 65 set I had no problem maxing crit damage and maintaining 70+ crit rate, I was even able to do it without using the crit damage gun or fatal blade. Just 70 bow and 60 bow. Don't forget you can get 10-16% crit damage boost on costumes and you don't need to use invincible variant stones on all weapons to achieve a consistent 70+ crit rate. Plus you can get as much as 18% crit rate from masters, 20 from stealth strike, about 20 from agi, 5 from buff, 6 from cape/accs which is 69% before even taking into consideration things like sniping or RM title or Invincible variants etc.
20% crit damage from AT + 40% crit damage pvp set +10% from costume + 16% from accs = 86% crit damage giving you a total of 236%, meaning you need 64% more to cap. You can get as much as 72% if you go all explosion variant in weps.
Basically my suggestion if your using pvp set would be to stone all your swords with explosion variants and to stone your 70 bow with explosion variants but stone the 60 bow with Invincible variants. 60 bow will be your go to weapon on xtals and you will use it to delay opponents from getting the xtal by hitting them with the knockback. 70 bow will be used everywhere else. And 38 gun can be useful if your well geared and and good at procing weapons. This setup should work fairly well with sprite set as well if you have to switch to it since you would need the crit damage stones due to lack of crit damage on the set. Also if you happen to manage to get gvg set you can use 60 bow more to maximise dps since if you can afford that set odds are you can afford to fort it high, so you can get away with 60 bow more than before.
edit; also if your using pvp set its best to use the combo of 70 and 60 swords, although you can even use 65 and 60 if you feel the extra crit rate would help. If using sprite set however its better to use 65 and 70 swords as you will need the crit rate of the 65 sword to compensate. As for gvg use same sword setup as pvp set.