They're already the most powerful weapon in the game. Heck, the devs just recently brought the TU mine up to par with them.
They do plenty of damage... if they hit anything.

The Avalons are intended to be use against large stationary targets. They are not for PVP and so on.

The balance is that they can reasonably hit a cappie or station turret but should be very easily avoided by the smaller ships. Speed is just not that important but they do need time to reach a target from a good distance.

1000m takes 17 seconds to cross at 60 m/s

Proximity fusing at 10m ?
US nukes use very accurate guidance and small payloads to minimise collateral damage while Russian Nukes use Poor guidance and large payload to wipe out an entire area.

Perhaps a serco version with a 30m Prox and triple yeild but no homing
and an Itani version with contact fusing, half damage and a moderate amount of homing?

Just a few pennies to toss about.

Tserco Bomba.

Want.