If the 64 team was having the same sources as Iga's team has now, i believe that they could beat Iga's 3D vanias blindfolded. 
Agreed. They had a handle on what makes Castlevania Castlevania, even if they didn't have the time and resources to implement it all. I mean when IGA got a second chance at 3D after LoI, he decided that what was missing was a Pokemon-like Familiar system in CoD.
That was the "key" element missing in LoI that would make a better 3D Castlevania. :

(Not more platforming or swinging over gaps or interactive level design, etc etc). It was a level-based Familiar system and more hallways than ever before that was needed. And, if not that, then a 3D fighting game (Judgment).
I enjoyed CV64 and LoI when I first played them. Recently, I went back and played both.
I found myself refreshed by CV64 in that the level designs actually used 3D space dynamically. IE: The clock tower actually has 3D gears you can stand on and take multiple paths through!
Meanwhile, I was shocked at how simplistic LoI was. The graphics and music were cool, but everything was so flat and the combat was more boring than I remembered. (And then it hit me...why can Leon walk in the air as he jump-whips--it looks ridiculous. The Belmonts aren't super heroes, and therefore, any future 3D combat system should be based on more realistic mechanics. It creates a better balance for the use of things like sub-weapons).
I think the gritty art direction of the CV64 world was more compelling and immersive than the more fantasy-esque, cut-and-paste worlds of IGA. Whereas IGA's are eerie, CV64 was downright creepy.
Now, I like that a camera control system was added to CoD, and the general idea of more combat options is nice, but the makers of CV64/LoD just had a much better grasp of what Castlevania
is in the classic sense. Castlevania does not = SotN. Symphony is a side-story, much in the same way that Megaman does not = Battle Network/EXE. Are both legitimate game formats? Yes. But the pedigree runs deeper than the latest trends, and that has to be observed. It'd be like someone deciding every new Mario game better follow Sunshine's example and have a water cannon, because that was an "evolution" of the series. I think Castlevania's been hamstrung in recent years by trying to repeat Symphony of the Night, when it was kind of a one time affair.
Regardless, the real test is coming. Castlevania for PS3 better not simply be 'God of War' or 'Devil May Cry' with a Castlevania skin. And it better not be a fanboy's tribute send-off to Alucard and SotN. It has to define itself, and feel like the soul of Castlevania in 3D, just as the N64 titles did.