Rebuilt 225 first start

With fuel in the carb and timing set, I'd think it will fire right up too.

I've read where some folks have pressurized the oil system through the relief valve on the pump. Did you pack the pump with Vaseline?

And BTW, one trick to get some oil in the filter is to assemble the engine complete and as a last step flip it upside down on the stand, fill the filter and install it, then flip the engine back right-side up. The filter will drain to the level of the standpipe but with a tall filter and the tall standpipe, it will be about half full.