I've replaced the water pump (impeller). It seems to still run hot and
no water out of the telltale. There is water coming out of the shifting
rod grommet. Wisner, who has a great website about repair, has
suggested that the thermostat needs cleaned and that the water jacket
might be plugged.

My questions:

Can I get the thermostat cover off without having to pull the whole
powerhead?
It looks like there are 2 bolts way down in the cover and they look to
be trouble.

Can the water jacket be flushed?
I could sure use some suggestions here.

My level of mechanic's expertise is such that I can do
brakes,thermostat replacement on my truck, recently

I feel like I can do this work.
This motor seems to run well and there wasn't much salt or corrosion in
the water pump area, the bolts all came out without shearing off.
Looks like it has been reasonably well cared for. I'd like to try and
take good care of it and do it myself.

Thanks for your help.

GMC