You don't need to rely on true Shoryu (i still struggle with the input and i've been playing
/
for months), the regular up-b is fine.
Ryu can kill easily with a bunch of moves, his problem is racking up dmg consistently because he's slow, it's hard to win neutral with him and his combos are short. An easy way to rack up dmg quickly is using the Shakunetsu Hadoken as combo finisher (jab 1-2 or hard jab into Shaku is pretty reliable/easy to execute).
Ken rely a bit more on the Shoryu but the Oosoto Mawashi Geri (the spinning kick to the face, same inputs as Ryu's Shakunetsu) is a really good kill move too.(Light dtilt - hard dtilt (to push the opponent in perfect range for the sweespot) - Oosoto is relatively easy to pull off).
Also about the true Shoryu, maybe you already know but the (close range) hard jab is probably the easiest way to confirm it. It has a ton of hitstun so you have the time to do the input (plus it hits like a truck, like around 20% iirc). Another tip, if you want to confirm a true Shoryu off of a d-air, it's easier to use the c-stick to do your d-air (so you don't have to 'reset' your main stick for the Shoryu's input).