1993 Toyota T 100 3 0 4wd Took Truck Shopfor Timing Belt Good 2 Months Later

3.0 4wd i took truck to a shopfor a timing belt all good 2 months later took it to the same shop for head gaskets when i got it back it had a bad miss the shop denied thieir screw up i done a compression check & #2 & #3 ex valves not closing took valve covers off and no clearance at all the rest but one are whithin tolerance and the one just over is there any specs to go by to just remove al lifters and shims and start there thanks for your input rod b