my 235 has the add on filter from gm that bolts on the manifold i used a tee to add it on many years ago napa has tha filters #1080 i beleive when i freshend up my 235 the insides were nasty in the old days you ran black label pennzoil then poured in a 1/2 qt of rislone to clean out the motor for about 10 muinutes then dumped the oil when i rebuilt the first time the whole inside of the engine was sludged and varnished beyond belief non detergent oil. i started using castrol 30 wt after the rebuild then when i rebuilt it again this motor has about 250,000 miles on it the insides were clean as a whistle. i now use 10w 30 castrol but i have installed a hydro cam and lifters no more feeler guage beatins a stock rochester b will handle any small beef up cam. just jet it accordingly cam selection will be limited. your 54 block has oil galleys for the hydro lifters and cam they switched with the second series in mid 55.also run an out side oiler to the rocker arms there is an oil plug in the block on the the rt side.where the oil comes up thru the pushrod gallery plug off the pipe remove it and reroute to the head. my motor is original with the truck.put a k&n filter setup on it it will flow alot more air to the motor. as far as valve springs you gotta use the cam lift + about .060" for proper spring the set up you don't want any coil bind.as far as overlap this ain't a hemi head so the valves are not going to ever touch each other.the intake might touch a piston on a high lift cam but his is a 235 here not a v8 the valves are at a slight angle but cutting the seats deeper than max spec will only make the rocker ratio wrong.at 1/2 lift the rocker arm will be in line with the center line of the rocker shaft.pushrod ball end of rocker arm and the end of the rocker arm where it touches the valve tip is correct geometry. too heavy of springs will rob h.p. and cause wear on the cam and lifters you don't need. you just need enough to do the job this is a tractor motor with a 120 lb heavy crankshaft torque in other words stump pulling torque. so a torque camshaft will be the best solution. also use valve seals on the head they make em.you can have the crank turned down for lighter wt but if your gonna go for all that then put in a small block and get it over with it will also handle the a.c.without a problem.
