I would only use slin if I was running high levels of PHARMA GH, over a gram of test and t4. No reason to use it with peptides, at least from what I know.
Regarding t3- people use it on cycle with drugs like tren, normally. Tren is very good at preventing catabolism, even when in a calorie deficit. However, if you have a surplus of fat to go, t3 off cycle is fine too. I wouldn't add it to a bulk, counterproductive.
As a wrap up here, do a lot of research before you buy these products. T3 abuse can permanently damage your natty production. But, I am glad you asked before running it.
Be safe.