what year 225?
Although - this thread has some numbers that are closer to matching what you posted:
http://www.forabodiesonly.com/mopar/threads/engine-serial-number.125797/
4225 T 312
1974 model year
225 CID
T for Trenton engine plant
312 = March 12, 1974
So maybe, combining the two posts,
the H means 1972
225 is the displacement
T is then Trenton engine plant
but 188??