Well find out if they make a solid spool first and do that. If not, then yes fill it solid because again, you don't need one side be locking and the other unlocked while trying to drag race. A solid spool is better for straight line racing.

Just take a look at alot of drag race specific cars and you'll see solid axles, no shocks, etc.

I'll keep checking in on you and help as much as possible. It should run hard. Why not a 2-speed though and what ratio is that single speed?