I would try a starting dose of just 25mg a day of 5htp, and see how you go. The 100-300mg doses recommended are way overkill IMO, and most likely just stated so you purchase more product. I would take it at bed time unless it causes insomnia, as it can cause sedation in some. Experiment with timings. It can also cause the most vivid dreams imaginable, which I generally liked. I remember I was crying in one dream, and when I woke up there was actually tears down my face! Wasn't even depressed at the time either- was taking for sleep. Take it on a completely empty stomach or it doesn't get absorbed, if you wasn't aware.
I can't comment on the ratios as I've never taken tyrosine.
A nutritious varied diet (which is surprisingly difficult to achieve- especially when depressed) will probably achieve better results over the long term than any amount of supplements IMHO, having done a lot of reading/experimenting in this area. I appreciate where you're at though, and certainly worth a go over pharmaceuticals if your situation isn't desperate.
Edit: wasn't sure if you was planning to or was already aware, but absolutely do not take SJW and 5HTP at the same time either, as you would be at risk for serotonin syndrome, which can be fatal.