I'm not all that sure about sheep manure myself. My gut is that your mix is gonna be a little hot. How old's the manure? Commercial product or, ah, home-crafted?
Do you know what the diet is?
I'd prob cut that back to maybe 20% manure, less if it's local, even less if it's young ( less than two years).
If you're thinking promix, why not skip the manure entirely? Grab some osmocote, some bone meal, and a little rock phosphate, mix em into yer promix, and away ya go. Or if the osmocote oogs you out, use worm castings

Promix has some lime in it already- lemme look at a bag tomorrow and I can give a better idea. Too lazy to get up.

Remember that adding perlite will increase aeration, which means lowering waterholding capacity. Tomatos outside can move a fair bit of water. Size pots accordingly. Then move up one size.

If ya got old coco kicking around, and it's long grain, you could mix it in instead of some of the perlite, or as an adjunct. If it's used, and been wet/damp for a while, you might want to cut back on the phosphate a bit, and add a little more bone meal. Or you might not.

In terms of dead simple, I've got Big Boys going right now in coco-peat-sphagnum mix, on the BioCanna stuff- feed once a week, water as needed. No pH check, no dicking around. And they love it. ( Like alien tomacco love it).

Lemme know about the manure.