Crankshaft pulley bolt rounded off 2004 Yaris 1.0 1SZ-FE

[Richplug]

Hi Guys and Girls

I have a  2004 Yaris with the 1.0  1SZ-FE engine

The timing chain was very loose and now has jumped therefore the engine is not starting (it jumped on turning off at idle)

i have bought a new timing chain kit inc the VVT gear and on going to fit same I have come across the way over tight crankshaft bolt

which whilst trying everything to loosen i have managed to round the head off ( stupid i know) and now need any suggestions on how to remove the damaged bolt, 

I dont have workshop access but was thinking of grinding the bolt head/washer off. 

Is this something someone has done and can advise me on?

I know it is an old car but it has just been put through an MOT which cost £380 tyres etc so really dont want to scrap it if i can possibly help it.

can anyone tell me if these engines are safe/ non interference(valves kissing pistons etc) engines as having invested MOT money and now a timing chain kit i don't want the expense of removing  the head unless absolutely necessary.  

Awaiting suggestions 

Richard