in more modern times… I find that the best all around pushrod engines end up being slightly undersquare.
case in point, I was able to make a 4.4 v8 pushrod with 360 hp approx and 20% efficiancy running on 95 ron that matches the ringamster requirements… and I have to admit I was impressed…
You should check out nialloftara’s engines, they take pushrod to the max. Of course, the figures you’re getting for the Ringmasters league is pretty darn impressive… should drop it in a car and see how it does and give him a real shock 
for a reason… I find that pushrod v8s have lots of character… must be the muscle car thing.
I have long stroke V8s aplenty too which one would you like?
Edit:
Can anyone explain why undersquare engines perform so well? (rhetoric question)
Pushrods make a good amount of torque at low rpms, but that drops off as the revs rise. A long stroke helps maintain power at higher rpms, so combine the two and you end up with a well balanced engine. Also remember that a smaller bore helps fight valve float which is the plague of pushrods, so using stroke to gain more displacement which would normally hurt mtbf at high rpms nets you plenty of power with out the cost as pushrods don’t rev high anyway. hope this helps. 
also: long stroke engines are more efficient, allowing to use a richer mix in the case of the ringmaster’s league.