ive built 1 engine before from 2nd hand parts. and have just rebuilt my current engine which i havent run yet.
still, i would definitely not say im experienced. but i can offer some guidance.
basically, the info you need is all in the 4age engine repair manual, which you can download for free online from a few places.
for some one doing the rebuild at home, there are a few steps/measurements/checks you can skip, but its all pretty clear once you start whats essential and whats not.
if you start with a decent engine, thats just tired, i.e no loud knocks, spun bearings, ect this is the best place to start for an amateur. this means in most cases you can just use new standard size bearings, after a visual inspection of the crank, and running your finger nail across the crank journals, to check for any deep scoring.
if you do find you have a crank that needs machining, you might be able to find an engine reco' place that will do the machining and then supply you the correct size bearings to suit. in qld ive inquired and JHH is happy to offer this service.
that just about covers big ends and mains.
oil pumps are best just replaced as a whole unit if you decide its necessary. try to use the latest model you can, im most cases this is ae101 20v. (works on 16v too) you cant use 111 as the tensioner arrangement for the timing belt is different.
little end bearings almost never need attention in 4a's. unless your motor has a funny light knock, which you have determined isnt coming from the mains/big ends, then dont worry about them.
head and block decking isnt necessary usually unless your engine has been over heated.
its easy to check cheaply though, with a straight edge and feeler guage (both cheap tools)
should note here be VERY careful removing head gasket residue. use a scraper with a razor blade, and then "roll up pads" for an die grinder if you have access to one. theyre small abrasive discs, use the soft ones.
ive replace a gasket in an engine before, and not bothered with the roll up pads, but i did you copper spray to aid sealing even with just a normal hg.
if youre going to use a thinner hg, then its probably wisest to have the head and block skimmed anyway, opinions vary a bit here, but the last thing you want is a leaky hg after youve just put your motor together.
as far as bores. 4a;s have very "hard" bores, are rarely every need to be bored out for oversize pistons.
as far as honing, this can be done at home. basically a hone is just meant to clean the bores and provide a slightly roughed up surface for the new rings to bed into. you will find you want obviously a variable speed drill to do it with, and do it at very low speed, moving up and down the bores quite quickly, as the hone marks are meant to be on around a 45* angle. if youre intimidated by this step dont worry, ive been quoted as little as $60 to have this done professionally.
as for pistons, a simple visual inspection seems fine. youre looking for any damage on top from pre-ignition/debris, and any excessive wear on the skirt.
thats all i can think of. the rest is in the book. never done any top end reco work, so cant advise on lapping valves, replacing valve stem seals ect.