I got my 73 type about a year ago for SWA. In my class there was a guy in the same situation as yours. He said that doing an ATP in a twin piston costs just a little more than the 73 type (4995$).
He had no major problems passing, the oral was straight forward and the check ride with no surprises.
So I would say that it might take you working a bit harder than the rest of your class but if you are motivated you can do it.