Kinda depends on what you're after.
If you want a full pressure oiling vintage looking 6, the engines you have are fine.
If part of what you are swapping for is more Gow (performance, HP, torque) then the 261 is a better deal.
If you want even more, the 261 can be bored as well as stroked (so can the 235, but the 261 can result in a larger combination still).
All the hot rod 235 parts will physically fit the 261 except the pistons (261 has a bigger bore stock).
