I assume you mean the tridem-axle 1978-1990 34's.
I agree that the last few feet make a difference in some backing maneuvers as the OAL is now significant. FWIW that is more a matter of getting used to it. But it will never be a 25' for not having to pay attention to trailer "swing" -- the tail "space" requirement in jack-knifed backing AND the room needed by a LWB truck -- but that is the price paid for the interior space. My combination is right at 65' (Texas RV maximum). Check the distances of yours, and note the TV RR axle center to TT axle center distance.
JimGolden or other Avion owners can tell you the hitch ball to TT axle center so you can do a "mock-up" to see how you feel about this extra length and turn/backing concerns against your pickemup. It's all about where one can put the TV rear axle to make it happen. The other length is TT axle center to rear bumper. Lay this out at your site and compare it with visual aids.
I don't in any way consider the TTL length to be a hindrance while on the road. Any road past a few "scenic" mountain highways where any trailed RV would be a taske to drive. I use truck stops to re-fuel so that part is a non-starter, too.
Best to have a long look at AVION floor plans. Interior width may not be as big as one of the porky late A/S trailers. And don't worry about interior cosmetics overmuch (I'm not thrilled with mine, either, but many other things are higher on the list for a 24-yr old TT).
The AVION interior has not the storage space of a classic Silver Streak (but nothing else does), so will the accommodations suit the way you use it day to day? My late model Sterling SS is not the same as the earler layouts (more an AVION sytle open-ness) so what storage is available is different. Maybe not as use-able to one like me. Still haven't moved in entirely as the lack of exterior storage (one compartment versus three) has stymied me (plus time to do it all). There will be more in the truck than I had originally anticipated.
I'd let that be my guide over all else: is the layout suitable? Yes, it is so big I can toss stuff all over the place and it is out of the way till I get to it.
There is always a market for this trailer brand and size so I don't see one losing anything. TXIceman bought an '89 34V the ex- and I looked at, and he upgraded it to 50A service with  A/C just for starters. New AL-KO axles. Sold it at asking to a knowledgeable buyer (see posts on IRV2) to buy a 5'er for retirement.
Never having to worry over shell separation, A-frame strength, etc, is a worth quite a lot. As to the anodized (unitl 1989) just remember that it can be prone to mineral staining, and we've not yet come up with a holistic solution there yet. I have high confidence that we will (except the worst examples). That said, no clear coat or filiform stuff. The roof has gaps to be sealed and these should be examined (most use ETERNABOND).
As I have looked at quite a few over the years I tend to note a correlation between those who "lose" the front window cover -- never replacing it -- and general decrepitude otherwise. CAYO still has them, I believe, so there really is no excuse. All tires not the same brand & age is another "warning".
I'd start all this with a PRO PRIDE hitch, no matter the TT eventuallly bought. I'd expect with that brand to have to comptelely rebuild the suspension first thing (as the stub axle is not an off-the-shelf item from DEXTER; or the AL-KO IS may be old).
1990 35' Silver Streak Sterling
; 9k GVWR.
2004 DODGE Cummins 305/555; 6-manual; 9k GVWR.
Hensley Arrow. 10-cpm solo, 18-cpm towing
Sold: Silver Streak Model 3411