I went through that ordeal last fall. I have a definite "long oval" head shape. I've had about 6 helmets in the past (3/4, full, and modular) and they all required "Adjustment" so they didn't give me headaches from pressure points. Previous helmet was a Nolan N-100 (I think) about 10 yrs old. Liner worn out, all the rubber seals had dry-rotted, + 10 yrs of use. I had to do a lot of "adjustment" to get that one wearable.
I looked through all the info I could find and tried the 2 "most long oval" modulars that were available. I wear a 7-3/8 or 7? hat size. I started with a Lazer Monaco. The shape was good, but they build all their sizes with one shell. Once I managed to get it one (barely) I actually tore my earlobe trying to get it off, and that was flexing it apart as much as I dared. Could work for you if you wear a small, or maybe med size. HJC RPHA Max was next (I too was trying for a modular), but way too round for my head, even in XL it still had front-back pressure points and loose at sides. I could have tried the high end Shoei modular (NeoTech?) but was tired of the swapping game (although Revzilla was very good about it) and the cost was sort of out of budget. Ended up with a Shoei RF-1100 in Lg. Not exactly perfect, but better than anything ever tried before. Revzilla was very good about exchanging the first 2 (all for no shipping charge either way). I had to go with thinner cheek pads (thinnest ones that are "specified" for a Lg helmet), and add a tiny bit of filler (3 mm mid-density foam) over the ear area under the liner to optimize the fit. I would have gone for the Arai Signet-Q, but the RF-1100 was on sale for $280 - the Arai would have been about $580. Have only had the new lid on in the house, but over an hour several times with no pressure points or headaches or neck aches.
I bought a pinlock clear shield (standard one is plain flat), a pinlock dark smoke shield, and two clear pinlock liners. I'm hopeful it will be quieter than the old Nolan - that thing - even behind a windscreen - was noisy. Exterior gaps and seams and shield fit was bad. I could put my hand across the top front area and all the noise went away.
There may be a modular out there that is a true long oval (maybe the NeoTech?), but I didn't have the patience to try 20 helmets (nobody within 200 miles actually stocks decent helmets) via mail order. The RF-1100 was definitely workable, so I stopped there. Hope that helps - and is not too discouraging..