Starter removal for 1994 Ford F-150 w/68000 miles

I have a 1994 ford f-150 with 68000 miles. I received it from my mother after my father passed away. The truck sat for several years only being started on occasion. The starter failed and all I got was a clicking sound from it. I replaced the starter solenoid but that has not helped. I tried to remove the starter but the bolts will not budge. I tried heat, penetrating oil and good old muscle but the bolts wont give. The heads are stripped now and even a pair of vise grip pliers wont budge them.

I was wondering, if I used a torch and cut the heads off, would there be enough bolt left to get a vise-grips on it to remove the rest and replace with new bolts.

Any other ideas would be helpful! I need help!