The TC02C generally uses side by side saddles, or shorty packs.
If you're wanting to move to a mid motor car anyway it might be easier just to buy a TC02C (or maybe the soon to be released TC02C Evo)
Your Mad Rat should accept end to end saddle packs anyway as they're normally equal the same length as a stick pack , you may need to dremel the battery strap slightly to access the terminals.
(EDIT: Kev, you're not allowed to reply while I'm still typing
)