I had a Traco 5 liter 90 degree sbc in a Lola T330 (A long time ago) and I bought a HRE flat crank motor as a replacement as the Traco was getting long in the tooth and the HRE motor was cheaper.
The car was 100-150 rpm down on the back straight at Road Atlanta with all settings the same (Wing and gears) but I was 1.5 seconds a lap quicker.
Much faster turn one through seven. Accelerated like a banshee.
I did notice that the rivets on the engine pontoons were getting a bit loose after the first two practices and qualifying. But this was a Lola after all and they were flexible flyers anyway.
The engine also went through rod bearings rapidly. We replaced them after every 1.5 hours running. (This was from
oil analysis results. Never showed copper but real close.)
I liked the motor....