That should be easily attainable, and as equally tame on the street.
If you’re going to keep it below 4500 RPM, the series 3 connecting rods and new bolts are entirely adequate. If you want to scream rev it, past 6000, then you should consider Carrillo rods.
IIRC, the Gran Turismo E Type that won a sports car championship against more modern competition back in the '80’s produced around 350bhp and , I think, had to use standard valve sizes and was using SU’s. 260 is probably a pretty unambitious figure with today’s technology, so should have plenty of low down urge. Envious 
I installed a short stud 4.2 in my 150 and I love the extra torque, my problem is I have to install the original 3.4 someday. Maybe that’s when I sell it.