There are not a lot of choices on the 250/292. Do you have the temp sender behind the bypass hose? There are several different thermostat housings, so I'll describe where to connect. For the hot water to you can get a hose 'T' and place it on the upper heater hose. You can also put a threaded 'T' on the upper heater hose by removing the barb for the hose. This can also be done at the temp sender, but the the temp gauge my error if you have one. Both of the connections mentioned will get you hot water from the block. There is also a thermostat housing that has three threaded ports were the bypass and temp sender are, I have one from a 250, haven't tried fitting it to my 292 yet. There are two places to put the water back in the system. The first would be the lower heater hose with another hose 'T'. The second would be on the drivers side of the block back by where the bell housing mounts about 4-6 inches above the pan there is a threaded plug to the water. If you want to plumb it like Old Bert did then you probably want to use the threaded fittings. IIRC the heater hose barb is 1/2 npt, and the plug on the bottom of the block is 3/8 npt. Orchard Supply has a good selection of brass fittings. The hose 'T's might be little difficult to find, I have substituted threaded fittings and put my hose clamp over the threads. If I missed something hopefully someone will catch it.
Larry