[v8volvo]

Nice find, the turbo motor will definitely be an improvement as a starting point. Someone might want the cruise control fixtures if you don't use them (could swap the non-cruise setup from your old engine over). Particularly folks in Europe where most cars were for some reason sold without cruise like to retrofit them.

Sounds like you got all the life your old motor was able to give with some field engineering, impressive it was able to get back on the track after all that. But it sounds like its days are numbered if it started to crack the block. Block cracking around the head bolt bosses was a well known problem with the early 1980-only D24 engines that used 11mm head bolts (with a 6pt inhex head rather than the triple square 12pt head that the later engines with 12mm torque-to-yield type bolts had), but pretty rarely seen on the 1981 and later engines produced after they upsized the hardware. I wonder if you have the early motor? What type of bit do the headbolts take on yours? Or maybe your usage demands just found the limits of the equipment either way.

Most of the time on these engines a gradual failure of the headgasket first causes overpressurization of the cooling system without any poor running symptoms, then later can lead to coolant intrusion into the cylinders. But a volcano of coolant out of the radiator cap when the engine is under load is the first sign, even if the engine still starts and runs fine.