i need a realistic answer on what to do next. i got my head resurfaced with new plugs,seals, everything is new... 2 weeks later i replaced oil pan and gasket, filled it up with fresh oil and new filter, drove around town and the timing belt snapped off. my friend said its the oil pump so i bought a new one with a timing belt too but not sure what to do....

is it better to replace the whole block or replace one part at a time???

 

Honestly, if your timing belt came off while under load I wouldn't be surprised you bent your valves at best. Worst case would be damage to the pistons/rings. Unfortunately simply changing the water pump + timing belt would not suffice at this point. I would check to see if you bent any valves first before slapping new parts on there. A simply compression test should help you determine what route to take next. Best of luck!