re the thermostat. you'll often find an engine will run hotter without one, the reason being with no restriction (an open 'stat has a smaller hole than no 'stat) the water is allowed to flow faster. this might seem a good thing but the water 'needs' to be in the radiator long enough to transfer heat which if it flows too fast it can't get done. if you're still struggling with heat try a 'stat with the middle/guts cut out which will be a restriction to slow the flow.
neil.