is jack under oil pan enough to support whole motor?

well i need to lower the sucker 6" to get at the stuck tensioner bolt so i can slip the belt back on. will the jack under the oil pan be sufficient enough?

also if you have any tips i could use it. currently reading through helmes/haynes… looks like i just need to remove the mounts and disconnect some hoses and connectors. already got the distributor and ps unit/cams off

Yes, but get a big block of wood in between the jack saddle and
the oil pan to spread the load.