I got the stroker kit from Speed-O-Motive, Inc. I will not use them again. Strokes out to 3.750 with rod length of 5.565. Since no one really makes high performance heads for the 305 I had these ported and put in stainless valves and roller rockers. Block and crank grinding, crank balancing, head porting and long block assembly were done by Kurt Hackendorf at Eastside Machine, 13209 NE 126th PL BLDG D-Suite 440 Kirkland, WA 98034 425-820-5193.