RhodesCD,
Since you chose 98tm ohv heads my advice is that you use 2.9L headers and have the ports matched to them. Ford cut the 94 and 95tm exhaust ports perfect for 2.9L headers but the inlets to the exhaust manifolds they used were oversized to try and trick/beat emissions; this ruined the exhaust velocity as will a set of 4.0L headers.
To be clear bpsinned is using 90tm heads in a 97 4.0L; he can safely add 94, 4.0L OHV pistons and run very near stock compresion. He can use 4.0L SOHC flat tops and raise the compression a whole point because he is using the big dish 90th heads.
With 97TM HEADS you can use 97 ohv pistons and mill the heads 0.030" and realise a full compression point. I have been told that a 97 EEC will run 95 or 97 4.0L ohv pistons no problem but that it will not get along with 94 shallow dome pistons and using SOHC 4.0L pistons is definitely not recommended for that EEC.
Neither of you need more than #19 injectors; they are supposed to be plenty through 250hp.
bpsinned,
If you haven't bought your cam or springs yet, I can help you save some money. My custom reground cam only cost $200 including shipping both directions from Oregon Cam Grinders of Vancouver Wa (they offer both Comp Cam profiles). My springs are a double set used in Ford V8's which worked out perfect for the new lift needs, the set was only $80. I have the part number if you are interested. I also have the cam specs that I'm using, though they are specific to the flow characteristics of my engine and used with an automatic.
I strongly urge you both to consider having your stock T/B bored, though not the cheapest procedure, that extra 3hp across the RPM band is a solid gain!!!
Also, since you are both stepping into higher compression power, don't skimp where money is best spent; spend the extra couple dollars and get the ARP piston rod bolts. If you are adding headers, Stage 8 offers great locking header bolts; there is nothing better than torquing header bolts once, FOREVER
FYI; the heads need a little work but of the 4 pieces that lower intake manifold came back the lightest. Just like with it's sibling the 2.9L, the lower intake manifold required the most material removed.