I used Kung Fu as a main loadout and used a few abils from Aikido and Karate aswell.I would shoot him with a victory rifle on speed just before ILing him, with some luck he would get dazed or staggered. If Dazed I used Sky High Sidekick then DMS. Staggered I used Piston Kick then Ki Punch.After that I would sit around on grab tactics and use Triple Front kick then Guard breaker in a row when he got off balance. If I missed him in any round I would use Iron Guard or Overhand Smash the round after to keep my defense up or drop his defense/accuracy. I used MA prowess with all my state specials if I could.If he was getting low on health I'd pop MA prowess then use Sky High and follow up with a string of specials to try finish him quick. With a little luck I wouldn't need to use any health pills but it's ok to have some as backup just in case. TB's also help out a lot.If you get off balance use Consistent Technique cause if he uses Tomo Nage on you there's a good chance he can one hit kill you with it.
It might not be pure, but spending a few points on Proxy 1 can help a lot. It won't do any damage but it's a good source of extra states for your specials.
Going in there at level 40 is the easiest option, Kano. One level is more than enough time to collect a decent-sized haul. You could even go in just before hitting 41, and spend a few hours easily killing Tengu at that level. You wouldn't be able to go back in, obviously, but the kills are a lot easier.
As for tactics, you should be fine in IL as long as you don't spam ability after ability and run out of IS. Sometimes, Tengu will hit Iron Body (or is it the other one) and thus your damage output will be significantly reduced. Ride that out, though, and you'll do fine. You shouldn't really need to roll-out unless Tengu is proving especially tough to beat (it happens) and you're out of health pills.
Okay for a start you don't need to be using Intensify Attacks or Gaussian Blur. Before you go in you need to trim your load and hotbars to include only the abilities you'll be needing for the encounter. I can also see you've been using abilities as if Tengu was a normal NPC, this isn't going to work. Stick to normal attacks until you get a state and then fire a state-combo as other abilities usually aren't going to do enough damage to matter. It's good that you're using speed kung-fu but if you find Tengu winning too many rounds you might want to back it up with a Tactic Booster. The trick with this sort of encounter is to be patient and let the numbers work themselves out, don't rush for a kill or you'll blow all your energy at once.
I only had GB up because on Vector all the evade combat helps when your < 50. I don't use IA, only MAP. I was also only using state attacks with the Sims help like you said. Unfortunately I don't have too many places to get pills/boosters as the Marketplace never has anything just like it never has, and I don't have any skills leveled after I reactivated. [Which is the main reason for farming in the first place]I'll go ahead and hit 40 before trying again, and load some Karate and Akido as well.