Not sure how a balancer slips a tooth. I was very careful to get the cam aligned with the crank when replacing the timing chain. Looks like a Doorman balancer is about $130. Also looks like the one off of my 170 will not work:-(.
Paint pen mark across the balancer is good for checking slip...over time..but that will not fix the 90lbs compression issue...so I'd not even focus on that atm.
Do yourself a favor take the valve cover off...take the rockers off.. go get a ruler and place it edge down across the valve stems and tell me how big a gap there is between all the intake valves and which exhaust valves are the highest ones holding up the ruler.
That's telling you your valves are sunk ,the higher the stems... compared to others/intakes... the more sunk that valve is... And the further it sinks... the more it can not cool and the less it flows..and does not seal.... volume grows larger as a byproduct and the compression gets weak ..and that weak compression also leaks past the exh valve.
You might be able to get away with just a cylinder head job on this, might.
The results will determine this.
