question on head exhaust port size

here's where my confusion lies...TTI says:
*For 273-318 Small-port cylinder heads, with the port diameter 1.09w x 1.55h. Applications with these small-port cylinder heads, will require modification to the ports for our headers to seal properly. Additional material will be added to the ports for headers to seal properly. Modification will be done prior to coating.
Are 1970 318 heads considered small port? I know alot of guys here have used TTI here.
Just trying to determine if these are special order or std.
http://www.ttiexhaust.com/MoparClassics-Headers/340-Step/TTi340.htm