My Lawn boy Snowblower 1986 vintage 8 HP tec snowking engine went bang. Did not punch hole in block but pull cord no piston movement. How much time and material ballpark estimate to install new rod? Engine had plenty of oil but over reved I suspect. Do I spend time money fixing or just look for another engine in NH? Thanks guys.

A connecting rod should be around $30 and would take about 1-1/2 hours to replace.
If the piston is damaged you'd have another $50 in a piston assembly. I'd check it out carefully for any damage to the block before ordering any parts. If there's aluminum smeared on the crankshaft journal it wasn't getting enough oil. If the journal is discolored it's been hot. Mic it to be sure it's not out of round.

Sometimes a short block would be the cheaper way

It's hard to say without a tear down and inspection, but the engine is 20 years old so I would seriously consider a new replacement engine if the rest of the unit looks good. You might want to check out parts availability on the rest of the unit, if parts are scarce for it, then it might be best to replace the entire unit.