It's an O-360-A1A from Lycon, 350 hours to date in an RV-7. Best engine I've ever operated: smooth, powerful, even CHTs and EGTs. What you need to specify is Lycoming steel cylinders, flow matched and polished, and the older "performance" cam. I also specify a Superior sump because it looks like it would flow better, roller cams if you want them. The bottom can be Lyc or ECi.
Lycon will also advance the cam 3 degrees to accompany 10:1 compression if you want it. Many of the builders around here prefer Lycon and order all these features, but the price does start to build. Lycon's strength is extracting horsepower from Lyc cylinders.
ASP will custom build an engine any way you want, and will guide you as to what provides the most bang for the buck.
I always call Mattituck, but they seem focused on assembling the parts and applying some pricey fluff. There's considerable black art in building a good engine, and their reputation is outstanding. But I like tricking out an engine and Lycon and ASP will do just that.
But, doing business with Lycon is very, very, VERY, difficult. Kenny Tunnell is the focus of absolutely everything. Customer communication is poor, and time quotes are smoke. You'll get a good engine, but it will be a frustrating process. That's the reason that two days ago I ordered a custom 375 from ASP (Carb, 9:1, cam, sump, Lyc cylinders w/3-angle grind, rollers). OUTSTANDING customer oriented shop.
John Siebold