Back in the day, I was following Gale Mcmillan here in TFL rifle country with his round bottomed Rem 700s and Bart Bobbitt on rec.guns with his flat bottomed Win M70s. They both returned messages to me, but that was 4 computers ago.
Using De Haas's book "Bolt Action Rifles" 4th edition, I have compiled a list of attributes of these two rifles and give the Howa a 50% rating for being in between.
the 98 Mauser has:
1) flat bottomed receiver to take torque from rifling
2) controlled feed
3) claw typed extractor
4) safety on firing pin, often modified to be 2 or 3 position M70 type
5) multi stage gas filter on firing pin hole
6) bolt handle is integrally forged as part of bolt body
7) safety lug below rear bridge
8) integral recoil lug
9) knife ejector in bolt lug slot
The rem 700
1) receiver made from round tubing
2) push feed
3) little wimpy extractor
4) safety on trigger
5) simple bolt
6) bolt handle tacked on with screw and solder
7) nothing
8) recoil lug is a modified washer that is captured by the receiver and barrel
9) plunger ejector
Of the ~100 bolt action covered in the above book, they seem to all be on the spectrum somewhere between the simple Rem700 and the complex 1898 Mauser design.
The Howa 1500:
1) flat bottom receiver
2) push feed
3) short claw extractor is bigger than rem, but smaller than M98
4) three position bolt safety
5) simple bolt
6) Integral bolt handle
7) nothing
8) integral recoil lug
9) plunger ejector
I would give the Howa Mauser scale = ~50% Mauser
I would give the Howa Rem700 scale = ~50% Rem700