Someone was kind enough to call my house with Jimmy Amrheim's phone number. I called him and got to chat with him after about 50 years. He did say that we ran that slant 6 in his car at El Mirage and it set a record. That part doesn't surprise me because how many people would run a 3 liter engine in a roadster. Must have been a easy record. I forgot to ask him how fast it went. So Stan Back is correct about seeing the roadster at El Mirage with the "no butterflies" slant 6.
Going back and remembering about this engine brought to mind how blessed I was that a number of owners trusted me to drive their stuff through the years. I got to sit in front or behind a fair amount of different engine combinations. Actually probably more than my share. The following is my list as I remember.
Ford: V-8 60, 144 Falcon, Boss 302, Gurney/Westlake, and a pair of inline SOHC 427 Cammers.
GM: Chev 4 cyl, Small block, Big block, overhead Pontiac 6 cyl, V-6 Buick, and a 215 aluminum Olds.
AMC: 287 V-8
Chrysler: Slant 6, 392, 273, and a 277 Plymouth.
Aircraft Engines: 1710 Allison, Rolls-Royce 1650 Merlin, and a 2240 Griffon.
Note: All of these engines except one did have butterflies.