According to my books, that's the height for the early 273. Sorry, I don't have data on the Magnum piston. The 67-69 318 was 1.759 from the same source. These pistons have 4 valve reliefs cut into them. Compression of the the 318 of that era was 9.2:1.
The other way to raise compression is to reduce the volume of the combustion chamber. Milling the heads is one way to do this. It may be cheaper to get heads off of a 66 or 67 273 or 67 318 (57 cc). In 68, the heads were enlarged to 60 cc and remained this way through the end of 74 production. At one point, Mopar was touting using the Fast-burn heads of 85 & 86 for 318 build ups where stock valve size needed to be retained. These heads have 62.6 cc chambers. These heads, with no change in the piston, caused compression to rise from 8.4:1 to 9:1.
Hope this is helpful
