Was thinking after many fruitless Google searches, could a stock from a different Enfield series be fitted to my No.4? I have have seen many No.1 stocks fairly priced. All the No.4's have been outrageously overpriced, like $300 for cracked rough shape stocks. Just me tumbling things around in my head.
The buttstocks of the No. 1 and 4 Series are interchangeable, the forearms are not and neither are the handguards without doing stuff that would basically guarantee stock problems (gluing and pinning infills, etc.)
GunnyUSMC could probably do it and even make it look somewhat right but due to time and effort, better to get a genuine product.
Lysander posted the correct handguards for your rifle, there is no long handguard for the No. 4 as the No. 4 does not have the rear sights mounted on the barrel--it uses a rear receiver sight. The No. 1 used such combined with a short one. Easy distinction is that No. 1 has a long and short, No. 4, roughly equal in length. The No.1 handguards have delicate ears to protect the rear sight, the No. 4 does not. Someone might have bubba'ed it to do so by mounting some sort of rear receiver sight on the barrel but that is not as issued. The No. 1 has a thinner barrel than the No. 4 (leaving aside Lithgow heavy barrels) so the barrel profiles are different.
The reason that you are seeing a lot of No. 1 forestocks is Indian (the country) sourced surplus rifles and reproduction stocks. The No. 4 right now does not have large numbers of stocks coming in from India and apparently few reproductions. Supply and demand means that No. 4 stocks will be higher.
If you are intending wood use for hunting, there is little utility in trimming out the rifle in full gear using an expensive forend (aka forestock). You can find a RamLine synthetic stock set for much less than a forestock etc. and feel at ease doing things like glass bedding the receiver etc. to get the most out of it for your no. 4.
http://www.ramlinestocks.com/ramlinestocks.html#Carbine
Military rifles had handguards to protect hands from rapid fire which was especially important to the Brits under their Mad Minute. The military stocks were fitted carefully to the rifles either at the factory or by armorers and its two piece design is rather complicated to accurize. As Alex A mentions, Peter Laidler's tutorials on the British Military's way on milsurps.com Enfield subforum are the best way to fit a military stock. There is another book by Roger Wadham that is available and some of his methods were NOT used by the military but often by very expensive gunsmiths who "improved" what the military had wrought. Skennerton also co-authored a book on it that is between the two books mentioned. This may be out of print now.
On your no. 1, it might be able to be restored if there is no receiver recess setback. If there is not, you might try having a gunsmith fit a new bolt head and/or bolt body which is covered by Laidler in the Milsurps forum. Unlike the No. 4, the no. 1 bolt heads are not numbered, those stamped S were designed to be replacement bolt heads and then adjusted down to size to fit the headspace. If your headspace is excessive, then it will definitely shorten your brass life.
One last thing, are you firing Wolf's steel cased ammo? That would be the only bi-metal bullet with steel cased commercial ammo around and I believe it uses FMJ bullets to boot. At the age and storage of surplus ammo, it is not really worth shooting for hunting purposes using FMJ projectiles. If that worries you, then fire Prvi Partisan .303 which is not a whole lot higher in cost but does not use steel in their bullets or brass. They did have hunting softpoints and the like as well as do other commercial ammo makers.
