Hi there,
I have recently been building up my B44 (as I am new to the sport) with some help from the fellow club members at the Silverstone club.
My advise would be this (others will think differently) as I have found it to be fun and a good learning curve:
Motor
I have two motor both 2nd hand, the first is an Orion Ortex 10.5t which is getting me started, the 2nd when I am feeling happier with the set-up and want to go faster is a Speed Passion V3 6.5t.
ESC
The 2nd best bit of kit I am brought. This time from eBay and a Hong Kong supplier (perfect service by the way) it is a 120amp HobbyWing ESC - the good thing about this is that it is programmable (with the the help of a friend's HobbyWing software), meaning that I can keep up with the 6.5t and 8.5t cars at my club. Plus HobbyWing is a re-badged Speed Passion - without the price tag.
LiPos
My 1st best bit of kit, again off eBay and from overseas. They are BRCA legal 60c saddle packs - brilliant!!!!
On your point about saddle packs I believe that sticks won't fit in the B44 or B44.1
Hope that helps