Oeps, I was thinking with the LiFepo4 voltages.

We have good results with 3S in Hannibalito 4. That uses 9.6V GR01's with big wheels -170mm diameter.

For speedo's, if you want to keep it budgetfriendly, and "enough". The BotBitz 30A speedo will do the job. For later upgrades, TZ85's do the job in a lot of machines.

For more control, but with a pricetag, you have the Scorpion XXL , the larger Sabertooths or the in the UK unknown IB Fink mk 4.1