When i modified my A14 I used mazda UC 77mm dia pistons and a camtech 621 cam together with an A15 crankshaft, H89 head and a 38DGAS carb.

Cam came with double valve springs and a stated max RPM of 6800.

Big improvement in power felt and it pulls from 1500 or even less in 4th gear.
Not yet tested on Dyno as my next step is programmable ignigion but very happy with my mods.

621 or 639 grind would be a good choice noting the RPM limit of the later would require good pistons with if cast drilled oil return holes rather than slotted behind the oil rings for reliability if you used those max Revs often.

Full balance, shot peened rods and good forged pistons if looking at 7,000 rpm top end duties as well as decent ARP or like conrod bolts.

Twin Side draughts with the later cam would be good but look at around 10~10.5 compression to make useable power but still run pump gas and have the distributor advance curve re graphed to suit.

Decent Exhaust or if you can find one for fair money a GX type manifold with big bore downpipes and exhaust likely best around 50mm or two inch but no bigger.

So after searching on gumtree and ebay and other places i finally found a decently priced A14 that had a H89 oval port head.. but i want to rebuild it and work the motor a little bit

Has bits and pieces missing but its basically a long motor minus the manifold/carb/extractors/fuel pump/etc(most of it is stuff im going to be buying new anyways! )

I have pulled it apart and the bearings don't look so good and it has a pretty big ridge over the pistons so im considering boring the cylinders and putting over sized pistons in it as well as sending the cams away for grinding to make it sound a little lumpy when i get it running

Just wondering what kind of pistons people usually use for A14's when boring them out and aswell as what kind of cam i should be getting and also when getting the cam done should i be using upgraded valve springs (or double spring valves?)
i have been refereed by a friend to use Camtech to get my cams done, they have a list of varies types of grinds but im a little lost lol http://www.camtechcams.com.au/niss_4cyl_a12a14.html

I'm going to be getting DCOE webbers aswell

any help is appreciated :) thanks!