I ran 1/2 x 1/2 in most of my models. I put the bearers through the router table to thin them out behind the front bulkhead. I turned them into a 1/8 angle section and then braced across with balsa. It was no heavier than solid 1/2 x 3/8.
The additional cross sectional area of the fuse you gained gave a much stronger nose, less vibration and thus more stable engine runs.
I also tapered the bearers in from the front of the motor mounts so you could bring the fuse sides in to meet a spinner nicer.
It also yields a bigger tank bay, which I needed given I fed my piped 61's 20% nitro and they drank 7.5oz of fuel - but even on my 51 sized setups the extra tank bay area was nice. It becomes easier to fit fuel filters etc.
BG
Thanks for the replies, no there was minimal removed from the engine itself, just can't remember from exactly where & I don't think it involved limiting or reducing the cooling fins.
It's amazing how much fuselage bulk is increased with the use of 1/2" square mounts as opposed to the 3/8", that additional 1/4" sure adds unnecessary weight.
The modification to the mounting holes and lugs are simple enough with the "right" gear, so that should keep me happy.
By the way, the "new build" Enya 60's are a beautiful running & user friendly engine, typical of what you would expect from the Enya stable.