More than anything else pushrod clearance becomes an issue--heck a 3/8ths on some heads with a 1.5 makes you grind--1.6 ratio can drive you crazy grinding in a "delicate area" with risk of blistering or punching through
we use a lot of 1.7 and bigger on SBC circle track engines but it is just not needed on the Mops IMO what the heck will a magic 1.7 do that a well planned out 1.5 won't? IMO not that much and for sure hardly worth the extra effort
I know that if you are aiming to win a contest on the dyno when every single HP counts well then maybe but who needs a street strip engine on a 50 year old car that is that "scienced out"