When rallye and racing classes limit cars to use their original capacity 3 mains blocks.....
The 1000 is limited to 988cc even with overbores only 80cc extra is possible and in
under 1300cc class and is down 300cc to corollas and many other rallye cars.
The original A10 block can be bored to 76mm even 77mm with grouted bottom end then
an angled iron sump setup can be made as a bottom bearing carrier support then use
crossbolts from underneath it all which is alot of work but 300ccs is alot to give up to others.
Mazda 1300cc B series heads can also be made to fit when different cyl head rules are open.