I think the 1.8 only had roller lifters & cam

The roller rockers will help reduce a lot of valvetrain weight and friction allowing for easier/faster reving. The biggest issue with the stock rockers is their crude pivot points, metal pivoting on metal that oil can't really get too so there's some friction there, enough that the pivoting surfaces polish each other and can wear the rocker arm thin in the center.
Next step is to reduce valve & spring retainer weight so it can not just rev easier/faster but to also limit valve float and valvetrain wear. The stems of the valves are under so much pressure from the valve springs and the rocker arm that they polish the end of the rocker arm and eventually wear it thin too.
This may be all little things but they add up to pain-staking futures in the issue that I want to avoid. All of this with a roller cam will make my 1.9 reliable and relatively maintenance free after break-in, just have to do regular oil changes and the timing belt every 50k - probably can go longer if I reduce all the valvetrain weight & friction but I won't have that many miles over 5 years so I'd be replacing my belt before then lol
At the end there won't be much play, the hydraulic roller lifters still take care of that but I'm hoping there's a way I can make them "anti-pumps" so at higher rpms they're not losing hydraulic pressure thus lowering valve lift

In the states we don't have much access to performance cams or modern replacement cams, OEM NOS cams can be found on eBay pretty cheap but eventually they eat up lifters are wear out there lobes. I can get nicer cams from the UK but I'd be paying $200 just for a (EU) stock-profile cam after shipping, I could go bigger but then it's costing me $350 at which point I can have one custom made here in the states to any spec I want.
I blame poor construction too, as a $50 replacement cam from 1980s Ford won't be incredible lol But there's a lot of strain on the valvetrain that I know can be improved upon to help eliminate the extreme lobe & lifter wear we see so often in the flat-tappet CVHs. But I'll be using roller cams in as many CVHs as I can, virtually no lobe/lifter wear, a lot less valvetrain friction, more lobe duration, more aggressive lobe ramps, the only downside is them not being solid tappets you might not be getting up to 9500rpm but 7500 is no issue.

Event hough it will probably be my biggest limiting factor, I think my vacuum & mechanical distributor will be fine with some careful tweeking of the vacuum diaphragm and tuning the counter weights & springs. I'm really trying to keep a stock appearance under the hood, everything I've mentioned so far can be and will be well-hidden under the stock valve cover, stock timing cover, and big stock oval air box in addition to my custom headers that will pass as late 1982 optional equipment. If I wasn't keeping a stock appearance a custom CDI or computer-mapping system would certainly be on my mind!